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diff --git a/static/unix-v10/man1/ksh.1 b/static/unix-v10/man1/ksh.1 new file mode 100644 index 00000000..3ed7ef3b --- /dev/null +++ b/static/unix-v10/man1/ksh.1 @@ -0,0 +1,3787 @@ +.ds OK [\| +.ds CK \|] +.ds ' \s+4\v@.3m@\'\v@-.3m@\s-4 +.ds ` \s+4\v@.3m@\`\v@-.3m@\s-4 +.de P +.br +.. +.TH KSH 1 +.SH NAME +ksh \- Korn shell, the not standard command programming language +.SH SYNOPSIS +.B ksh +[ +.B \-acefhikmnorstuvx +] [ +.B \-o +option ] .\|.\|. +[ arg .\|.\|. ] +.br +.SH DESCRIPTION +.I Ksh\^ +is a command programming language +that executes commands read from a terminal +or a file. +.I Rsh\^ +is a restricted version of the standard command interpreter +.IR sh ; +it is used to set up login names and execution environments whose +capabilities are more controlled than those of the standard shell. +See +.I Invocation\^ +below +for the meaning of arguments to the shell. +.SS Definitions. +A +.I metacharacter\^ +is one of the following characters: +.RS +.PP +\f3; & ( ) \(bv < > new-line space tab\fP +.RE +.PP +A +.I blank\^ +is a +.B tab +or a +.BR space . +An +.I identifier\^ +is a sequence of letters, digits, or underscores +starting with a letter or underscore. +Identifiers are used as names for +.IR aliases , +.IR functions , +and +.IR "named parameters" . +A +.I word\^ +is a sequence of +.I characters\^ +separated by one or more non-quoted +.IR metacharacters . +.SS Commands. +A +.I simple-command\^ +is a sequence of +.I blank\^ +separated words +which may be preceded by a parameter assignment list. +(See +.I Environment\^ +below). +The first word specifies the name of the command to +be executed. +Except as specified below, +the remaining words are passed as arguments +to the invoked command. +The command name is passed as argument 0 +(see +.IR exec (2)). +The +.I value\^ +of a simple-command is its exit status +if it terminates normally, or (octal) 200+\f2status\^\fP if +it terminates abnormally (see +.IR signal (2) +for a list of +status values). +.PP +A +.I pipeline\^ +is a sequence of one or more +.I commands\^ +separated by +.BR \(bv . +The standard output of each command but the last +is connected by a +.IR pipe (2) +to the standard input of the next command. +Each command is run as a separate process; +the shell waits for the last command to terminate. +The exit status of a pipeline is the exit +status of the last command. +.PP +A +.I list\^ +is a sequence of one or more +pipelines +separated by +.BR ; , +.BR & , +.BR && , +or +.BR \(bv\|\(bv , +and optionally terminated by +.BR ; , +.BR & , +or +.BR \(bv& . +Of these five symbols, +.BR ; , +.BR & , +and +.BR \(bv& +have equal precedence, +which is lower than that of +.B && +and +.BR \(bv\|\(bv . +The symbols +.B && +and +.B \(bv\|\(bv +also have equal precedence. +A semicolon +.RB ( ; ) +causes sequential execution of the preceding pipeline; an ampersand +.RB ( & ) +causes asynchronous execution of the preceding pipeline (i.e., the shell does +.I not\^ +wait for that pipeline to finish). +The symbol +.B \(bv& +causes asynchronous execution of the preceding command or pipeline +with a two-way pipe established to the parent shell. +The standard input and output of the spawned command +can be written to and read from by the parent Shell +using the +.B \-p +option of +the special commands +.B read +and +.B print\^ +described later. +Only one such command can be active +at any given time. +The symbol +.B && +.RB (\| \(bv\|\(bv \^) +causes the +.I list\^ +following it to be executed only if the preceding +pipeline +returns a zero (non-zero) value. +An arbitrary number of new-lines may appear in a +.I list,\^ +instead of semicolons, +to delimit commands. +.PP +A +.I command\^ +is either a simple-command +or one of the following. +Unless otherwise stated, +the value returned by a command is that of the +last simple-command executed in the command. +.TP +\f3for\fP \f2identifier\^\fP \*(OK \f3in\fP \f2word\^\fP .\|.\|. \*(CK \f3do\fP \f2list\^\fP \f3done\fP +Each time a +.B for +command is executed, +.I identifier\^ +is set to the next +.I word\^ +taken from the +.B in +.I word\^ +list. +If +.BI in " word\^" +\&.\|.\|. +is omitted, then +the +.B for +command executes the \f3do\fP \f2list\^\fP once for each positional parameter +that is set +(see +.I "Parameter Substitution\^" +below). +Execution ends when there are no more words in the list. +.TP +\f3select\fP \f2identifier\^\fP \*(OK \f3in\fP \f2word\^\fP .\|.\|. \*(CK \f3do\fP \f2list\^\fP \f3done\fP +A +.B select +command prints on standard error (file descriptor 2), the set of +.IR word s, +each preceded by a number. +If +.BI in " word\^" +\&.\|.\|. +is omitted, then +the +positional parameters +are used instead +(see +.I "Parameter Substitution\^" +below). +The +.SM +.B PS3 +prompt is printed +and a line is read from the standard input. +If this line consists of the number +of one of the listed +.BR word s, +then the value of the parameter +.I identifier\^ +is set to the +.I word\^ +corresponding to this number. +If this line is empty the selection list is +printed again. +Otherwise the value of the parameter +.I identifier\^ +is set to +.BR null . +The contents of the line read from standard input is +saved in +the parameter +.SM +.BR REPLY. +The +.I list\^ +is executed for each selection until a +.B break\^ +or +.I end-of-file\^ +is encountered. +.TP +\f3case\fP \f2word\^\fP \f3in\fP \*(OK \f2pattern\^\fP \*(OK \(bv \ +\f2pattern\^\fP \*(CK .\|.\|. \f3)\fP \f2list\^\fP \f3;;\fP \*(CK .\|.\|. \f3esac\fP +A +.B case +command executes the +.I list\^ +associated with the first +.I pattern\^ +that matches +.IR word . +The form of the patterns is +the same as that used for +file-name generation (see +.I "File Name Generation\^" +below). +.TP +\f3if\fP \f2list\^\fP \f3then\fP \f2list\^\fP \*(OK \ +\f3elif\fP \f2list\^\fP \f3then\fP \f2list\^\fP \*(CK .\|.\|. \ +\*(OK \f3else\fP \f2list\^\fP \*(CK \f3f\&i\fP +The +.I list\^ +following \f3if\fP is executed and, +if it +returns a zero exit status, the +.I list\^ +following +the first +.B then +is executed. +Otherwise, the +.I list\^ +following \f3elif\fP +is executed and, if its value is zero, +the +.I list\^ +following +the next +.B then +is executed. +Failing that, the +.B else +.I list\^ +is executed. +If no +.B else +.I list\^ +or +.B then +.I list\^ +is executed, then the +.B if +command returns a zero exit status. +.TP +.PD 0 +\f3while\fP \f2list\^\fP \f3do\fP \f2list\^\fP \f3done\fP +.TP +\f3until\fP \f2list\^\fP \f3do\fP \f2list\^\fP \f3done\fP +.PD +A +.B while +command repeatedly executes the +.B while +.I list\^ +and, if the exit status of the last command in the list is zero, executes +the +.B do +.IR list ; +otherwise the loop terminates. +If no commands in the +.B do +.I list\^ +are executed, then the +.B while +command returns a zero exit status; +.B until +may be used in place of +.B while +to negate +the loop termination test. +.TP +\f3(\fP\f2list\^\fP\f3)\fP +.br +Execute +.I list\^ +in a separate environment. +Note, that if two adjacent open parentheses are +needed for nesting, a space must be inserted to avoid +arithmetic evaluation as described below. +.TP +\f3{ \fP\f2list\^\fP\f3;}\fP +.br +.I list\^ +is simply executed. +Note that +.B { +is a +.I keyword\^ +and requires a blank +in order to be recognized. +.TP +.PD 0 +\f3function\fP \f2identifier\^\fP \f3{\fP \f2list\^\fP \f3;}\fP +.TP +\f2identifier\^\fP \f3() {\fP \f2list\^\fP \f3;}\fP +.PD +Define a function which is referenced by +.IR identifier . +The body of the function is the +.I list\^ +of commands between +.B { +and +.BR } . +(See +.I Functions\^ +below). +.TP +\f3time \fP\f2pipeline\^\fP +.br +The +.I pipeline\^ +is executed and the elapsed time as well as +the user and system time are printed on standard error. +.PP +The following keywords +are only recognized as the first word of a command +and when not quoted: +.if t .RS +.PP +.B +.if n if then else elif fi case esac for while until do done { } function select time +.if t if then else elif fi case esac for while until do done { } function select time +.if t .RE +.SS Comments. +A word beginning with +.B # +causes that word and all the following characters up to a new-line +to be ignored. +.SS Aliasing. +The first word of each command is replaced by the text of an +.B alias +if an +.B alias +for this word has been defined. +The +first character of an +.B alias +name can be any printable character, +but the rest of the characters +must be the same as for a valid +.IR identifier . +The replacement string can contain any +valid Shell script +including the metacharacters listed above. +The first word of each command of the +replaced text will not be tested for additional aliases. +If the last character of the alias value is a +.I blank\^ +then the word following the alias will also be checked for alias +substitution. +Aliases can be used to redefine special +builtin commands but cannot be used to redefine +the keywords listed above. +Aliases can be created, listed, and exported with the +.B alias +command and can be removed with the +.B unalias +command. +Exported aliases remain in effect for sub-shells +but must be reinitialized for separate invocations +of the Shell (See +.I Invocation\^ +below). +.PP +.I Aliasing\^ +is performed when +scripts are read, +not while they are executed. +Therefore, +for an alias to take effect +the +.B +alias +command has to be executed before +the command which references the alias is read. +.PP +Aliases are frequently used as a short hand for full path +names. +An option to the aliasing facility allows the value of the alias +to be automatically set to the full pathname of +the corresponding command. +These aliases are called +.I tracked +aliases. +The value of a +.I tracked +alias is defined the first time the identifier +is read and becomes undefined each time +the +.SM +.B PATH +variable is reset. +These aliases remain +.I tracked +so that the next +subsequent reference will redefine the value. +Several tracked aliases are compiled into the shell. +The +.B \-h +option of the +.B set +command makes each command name which is an +.I identifier\^ +into a tracked alias. +.PP +The following +.I exported aliases +are compiled into the shell +but can be unset or redefined: +.RS 20 +.PD 0 +.TP +.B "echo=\(fmprint \-\(fm" +.TP +.B "false=\(fmlet 0\(fm" +.TP +.B "functions=\(fmtypeset \-f\(fm" +.TP +.B "history=\(fmfc \-l\(fm" +.TP +.B "integer=\(fmtypeset \-i\(fm" +.TP +.B "nohup=\(fmnohup \(fm" +.TP +.B "pwd=\(fmprint \- $\s-1PWD\s+1\(fm" +.TP +.B "r=\(fmfc \-e \-\(fm" +.TP +.B "true=\(fm:\(fm" +.TP +.B "type=\(fmwhence \-v\(fm" +.TP +.B "hash=\(fmalias \-t\(fm" +.PD +.RE +.SS Tilde Substitution. +After alias substitution is performed, each word +is checked to see if it begins with an unquoted +.BR \(ap . +If it does, then the word up to a +.B / +is checked to see if it matches a user name in the +.B /etc/passwd +file. +If a match is found, the +.B \(ap +and the matched login name is replaced by the +login directory of the matched user. +This is called a +.I tilde +substitution. +If no match is found, the original text is left unchanged. +A +.B \(ap +by itself, or in front of a +.BR / , +is replaced by the value of the +.B +.SM HOME +parameter. +A +.B \(ap +followed by a +.B + +or +.B \- +is replaced by the value of +the parameter +.B +.SM PWD +and +.B +.SM OLDPWD +respectively. +.PP +In addition, the value of each +.I "keyword parameter" +is checked to see if it begins with a +.B \(ap +or if a +.B \(ap +appears after a +.BR : . +In either of these cases a +.I tilde +substitution is attempted. +.SS Command Substitution. +The standard output from a command enclosed in +a pair of grave accents (\^\f3\*`\^\*`\fP\^) may be used as part or all +of a word; +trailing new-lines are removed. +The command substitution +\^\f3\*`\^cat file\^\*`\fP\^ +can be replaced by the equivalent but faster +\^\f3\*`\^<file\^\*`\fP\^. +Command substitution of most special commands +that do not perform input/output redirection are +carried out without creating a separate process. +.SS Parameter Substitution. +A +.I parameter\^ +is an +.IR identifier , +a digit, +or any of the characters +.BR \(** , +.BR @ , +.BR # , +.BR ? , +.BR \- , +.BR $ , +and +.BR !\\^ . +A +.I named parameter\^ +(a parameter denoted by an identifier) +has a +.I value\^ +and zero or more +.IR attributes . +.I Named parameters \^ +can be assigned +.I values\^ +and +.I attributes +by using the +.B typeset\^ +special command. +The attributes supported by the Shell are described +later with the +.B typeset\^ +special command. +Exported parameters pass values and attributes to +sub-shells but only values to the environment. +.PP +The shell supports a limited one-dimensional array facility. +An element of an array parameter is referenced by a +.IR subscript . +A +.I subscript\^ +is denoted by a +.BR [ , +followed by an +.I arithmetic expression\^ +(see Arithmetic evaluation below) +followed by a +.BR ] . +The value of all +subscripts must be in the +range of +0 through 511. +Arrays need not be declared. +Any reference to a named parameter +with a valid subscript is +legal and an array will be created if necessary. +Referencing an array without a subscript +is equivalent to referencing the first element. +.PP +The +.I value\^ +of a +.I named parameter\^ +may also be assigned by writing: +.RS +.PP +.IB name = value\^\| +\*(OK +.IB name = value\^ +\*(CK .\|.\|. +.RE +.PP +.PD 0 +If the integer attribute, +.BR \-i , +is set for +.I name\^ +the +.I value\^ +is subject to arithmetic evaluation as described below. +.PP +Positional parameters, +parameters denoted by a number, +may be assigned values with the +.B set\^ +special command. +Parameter +.B $0 +is set from argument zero when the shell +is invoked. +.PP +The character +.B $ +is used to introduce substitutable +.IR parameters . +.TP +\f3${\fP\f2parameter\^\fP\f3}\fP +The value, if any, of the parameter is substituted. +The braces are required when +.I parameter\^ +is followed by a letter, digit, or underscore +that is not to be interpreted as part of its name +or when a named parameter is subscripted. +If +.I parameter\^ +is a digit then it is a positional parameter. +If +.I parameter\^ +is +.BR \(** +or +.BR @ , +then all the positional +parameters, starting with +.BR $1 , +are substituted +(separated by spaces). +If an array +.I identifier\^ +with subscript +.B \(** +or +.B @ +is used, +then the value +for each of the +elements +is substituted +(separated by spaces). +.TP +\f3${#\fP\f2parameter\^\fP\f3}\fP +If +.I parameter\^ +is not +.BR \(** , +the length of the value of the +.I parameter\^ +is substituted. +Otherwise, the number of positional parameters is substituted. +.TP +\f3${#\fP\f2identifier\fP\f3[*]}\fP +The number of elements in the array +.I identifier\^ +is substituted. +.TP +\f3${\fP\f2parameter\^\fP\f3:\-\fP\f2word\^\fP\f3}\fP +If +.I parameter\^ +is set and is non-null then substitute its value; +otherwise substitute +.IR word . +.TP +\f3${\fP\f2parameter\^\fP\f3:=\fP\f2word\^\fP\f3}\fP +If +.I parameter\^ +is not set or is null then set it to +.IR word ; +the value of the parameter is then substituted. +Positional parameters may not be assigned to +in this way. +.TP +\f3${\fP\f2parameter\^\fP\f3:?\fP\f2word\^\fP\f3}\fP +If +.I parameter\^ +is set and is non-null then substitute its value; +otherwise, print +.I word\^ +and exit from the shell. +If +.I word\^ +is omitted then a standard message is printed. +.TP +\f3${\fP\f2parameter\^\fP\f3:+\fP\f2word\^\fP\f3}\fP +If +.I parameter\^ +is set and is non-null then substitute +.IR word ; +otherwise substitute nothing. +.TP +.PD 0 +\f3${\fP\f2parameter\^\fP\f3#\fP\f2pattern\^\fP\f3}\fP +.TP +\f3${\fP\f2parameter\^\fP\f3##\fP\f2pattern\^\fP\f3}\fP +.PD +If +the Shell +.I pattern\^ +matches the beginning of the value of +.IR parameter , +then the value of +this substitution is the value of the +.I parameter\^ +with the matched portion deleted; +otherwise the value of this +.I parameter\^ +is substituted. +In the first form the smallest matching pattern is deleted and in the +latter form the largest matching pattern is deleted. +.TP +.PD 0 +\f3${\fP\f2parameter\^\fP\f3%\fP\f2pattern\^\fP\f3}\fP +.TP +\f3${\fP\f2parameter\^\fP\f3%%\fP\f2pattern\^\fP\f3}\fP +.PD +If +the Shell +.I pattern\^ +matches the end of the value of +.IR parameter , +then the value of +.I parameter\^ +with the matched part deleted; +otherwise substitute the value of +.IR parameter . +In the first form the smallest matching pattern is deleted and in the +latter form the largest matching pattern is deleted. +.PD +.PP +In the above, +.I word\^ +is not evaluated unless it is +to be used as the substituted string, +so that, in the following example, +.B pwd\^ +is executed only if +.B d\^ +is not set or is null: +.RS +.PP +echo \|${d:\-\^\*`\^pwd\^\*`\^} +.RE +.PP +If the colon ( +.B : ) +is omitted from the above expressions, +then the shell only checks whether +.I parameter\^ +is set or not. +.PP +The following +parameters +are automatically set by the shell: +.RS +.PD 0 +.TP +.B # +The number of positional parameters in decimal. +.TP +.B \- +Flags supplied to the shell on invocation or by +the +.B set +command. +.TP +.B ? +The decimal value returned by the last executed command. +.TP +.B $ +The process number of this shell. +.TP +.B _ +The last argument of the previous command. +This parameter is not set for commands which are asynchronous. +.TP +.B ! +The process number of the last background command invoked. +.TP +.B +.SM PPID +The process number of the parent of the shell. +.TP +.B +.SM PWD +The present working directory set by the +.B cd +command. +.TP +.B +.SM OLDPWD +The previous working directory set by the +.B cd +command. +.TP +.B +.SM RANDOM +Each time this parameter is referenced, a random integer is generated. +The sequence of random numbers can be initialized by assigning +a numeric value to +.SM +.BR RANDOM . +.TP +.B +.SM REPLY +This parameter is set by the +.B select +statement and by +the +.B read +special command when no arguments are supplied. +.PD +.RE +.PP +The following +parameters +are used by the shell: +.RS +.PD 0 +.TP +.B +.SM CDPATH +The search path for the +.I cd +command. +.TP +.B +.SM COLUMNS +If this variable is set, +the value is used to define the width of the edit window +for the shell edit modes and for printing +.B select +lists. +.TP +.B +.SM EDITOR +If the value of this variable ends in +.IR emacs , +.IR gmacs , +or +.I vi +and the +.B +.SM VISUAL +variable is not set, +then the corresponding option +(see Special Command +.B set +below) +will be turned on. +.TP +.SM +.B ENV +If this parameter is set, then +parameter substitution is performed on +the value to generate +the pathname of the script that will be +executed when the +.I shell\^ +is invoked. +(See +.I Invocation\^ +below.) +This file is typically used for +.I alias +and +.I function +definitions. +.TP +.B +.SM FCEDIT +The default editor name for the +.B fc +command. +.TP +.SM +.B IFS +Internal field separators, +normally +.BR space , +.BR tab , +and +.B new-line +that is used to separate command words which result from +command or parameter substitution +and for separating words with the special command +.BR read . +.TP +.SM +.B HISTFILE +If this parameter is set when the shell is invoked, then +the value is the pathname of the file that will be +used to store the command history. +(See +.I "Command re-entry\^" +below.) +.TP +.SM +.B HISTSIZE +If this parameter is set when the shell is invoked, then +the number of previously entered commands that +are accessible by this shell +will be greater than or equal to this number. +The default is 128. +.TP +.B +.SM HOME +The default argument (home directory) for the +.B cd +command. +.TP +.B +.SM MAIL +If this parameter is set to the name of a mail file +.I and\^ +the +.B +.SM MAILPATH +parameter is not set, +then the shell informs the user of arrival of mail +in the specified file. +.TP +.B +.SM MAILCHECK +This variable specifies how often (in seconds) the +shell will check for changes in the modification time +of any of the files specified by the +.B +.SM MAILPATH +or +.B +.SM MAIL +parameters. +The default value is 600 seconds. +If set to 0, +the shell will check before each prompt. +.TP +.B +.SM MAILPATH +A colon ( +.B : +) +separated list of file names. +If this parameter is set +then the shell informs the user of +any modifications to the specified files +that have occurred within the last +.B +.SM MAILCHECK +seconds. +Each file name can be followed by a +.B ? +and a message that will be printed. +The message will undergo parameter and command substitution +with the parameter, +.B $_ +defined as the name of the file that has changed. +The default message is +.I you have mail in $_\^. +.TP +.B +.SM PATH +The search path for commands (see +.I Execution\^ +below). +The user may not change +.B \s-1PATH\s+1 +if executing under +.I rsh +(except in +.I .profile\^ +). +.TP +.SM +.B PS1 +The value of this parameter is expanded for paramter +substitution to define the +primary prompt string which by default is +.RB `` "$ \|" ''. +The character +.B ! +in the primary prompt string is replaced by the +.I command\^ +number (see +.I Command Re-entry +below). +.TP +.SM +.B PS2 +Secondary prompt string, by default +.RB `` "> \|" ''. +.TP +.SM +.B PS3 +Selection prompt string +used within a +.B select +loop, by default +.RB `` "#? \|" ''. +.TP +.SM +.B SHELL +The pathname of the +.I shell\^ +is kept in the environment. +At invocation, if the value of this variable contains an +.B r +in the basename, +then the shell becomes restricted. +.TP +.B +.SM TMOUT +If set to a value greater than zero, +the shell will terminate if a command is not entered within +the prescribed number of seconds. +(Note that the shell can be compiled with a maximum bound +for this value which cannot be exceeded.) +.TP +.B +.SM VISUAL +If the value of this variable ends in +.IR emacs , +.IR gmacs , +or +.I vi +then the corresponding option +(see Special Command +.B set +below) +will be turned on. +.PD +.RE +.PP +The shell gives default values to +\f3\s-1PATH\s+1\fP, \f3\s-1PS1\s+1\fP, \f3\s-1PS2\s+1\fP, \f3\s-1MAILCHECK\s+1\fP, +\f3\s-1TMOUT\s+1\fP and \f3\s-1IFS\s+1\fP, +while +.SM +.BR HOME , +.SM +.B SHELL +.SM +.B ENV +and +.SM +.B MAIL +are +not set at all by the shell (although +.SM +.B HOME +.I is\^ +set by +.IR login (1)). +On some systems +.SM +.B MAIL +and +.SM +.B SHELL +are also +set by +.IR login (1)). +.SS Blank Interpretation. +After parameter and command substitution, +the results of substitutions are scanned for the field separator +characters ( +those found in +.SM +.B IFS +) +and split into distinct arguments where such characters are found. +Explicit null arguments (\^\f3"\^"\fP or \f3\*\(fm\^\*\(fm\fP\^) are retained. +Implicit null arguments +(those resulting from +.I parameters\^ +that have no values) are removed. +.SS File Name Generation. +Following substitution, each command +.I word\^ +is scanned for +the characters +.BR \(** , +.BR ? , +and +.B \*(OK\^ +unless the +.B \-f +option has been +.BR set . +If one of these characters appears +then the word is regarded as a +.IR pattern . +The word is replaced with alphabetically sorted file names that match the pattern. +If no file name is found that matches the pattern, then +the word is left unchanged. +When a +.I pattern\^ +is used for file name generation, +the character +.B . +at the start of a file name +or immediately following a +.BR / , +as well as the character +.B / +itself, +must be matched explicitly. +In other instances of pattern matching the +.B / +and +.B . +are not treated specially. +.PP +.PD 0 +.RS +.TP +.B \(** +Matches any string, including the null string. +.TP +.B ? +Matches any single character. +.TP +.BR \*(OK \^.\|.\|.\^ \*(CK +Matches any one of the enclosed characters. +A pair of characters separated by +.B \- +matches any +character lexically between the pair, inclusive. +If the first character following the opening "[ \|" +is a "! \|" then any character not enclosed is matched. +A +.B \- +can be included in the character set by putting it as the +first or last character. +.PD +.RE +.SS Quoting. +Each of the +.I metacharacters\^ +listed above (See +.I Definitions +above). +has a special meaning to the shell +and cause termination of a word unless quoted. +A character may be +.I quoted\^ +(i.e., made to stand for itself) +by preceding +it with a +.BR \e . +The pair +.B \enew-line +is ignored. +All characters enclosed between a pair of single quote marks (\^\f3\(fm\^\(fm\fP\^), +except a single quote, +are quoted. +Inside double quote marks +(\f3"\^"\fP), +parameter and command substitution occurs and +.B \e +quotes the characters +.BR \e , +.BR \(fm , +\f3"\fP, +and +.BR $ . +.B +"$\(**" +is equivalent to +\f3"$1 \|$2\fP \|.\|.\|.\f3"\fP, +whereas +.B +"$@" +is equivalent to +.B +"$1"\| +.B +"$2"\| +\&.\|.\|.\^. +.PP +The special meaning of keywords can be removed by quoting any +character of the keyword. +The recognition of special command names listed below cannot be altered +by quoting them. +.SS Arithmetic Evaluation. +An ability to perform integer arithmetic +is provided with the special command +.BR let . +Evaluations are performed using +.I long\^ +arithmetic. +Constants are of the form +\*(OK\f2base\f3#\^\f1\*(CK\f2n\^\fP +where +.I base\^ +is a decimal number between two and thirty-six +representing the arithmetic base +and +.I n\^ +is a number in that base. +If +.I base\^ +is omitted +then base 10 is used. +.PP +An internal integer representation of a +.I named parameter\^ +can be specified with the +.B \-i +option of the +.B typeset +special command. +When this attribute is selected +the first assignment to the +parameter determines the arithmetic base +to be used when +parameter substitution occurs. +.PP +Since many of the arithmetic operators require +quoting, an alternative form of the +.B let +command is provided. +For any command which begins with a +.BR (( , +all the characters until a matching +.B )) +are treated as a quoted expression. +More precisely, +.B (( +\&.\|.\|. +.B )) +is equivalent to +.B let\^ +\f3"\fP \|.\|.\|.\f3"\fP. +.SS Prompting. +When used interactively, +the shell prompts with the value of +.SM +.B PS1 +before reading a command. +If at any time a new-line is typed and further input is needed +to complete a command, then the secondary prompt +(i.e., the value of +.BR \s-1PS2\s+1 ) +is issued. +.SS Input/Output. +Before a command is executed, its input and output +may be redirected using a special notation interpreted by the shell. +The following may appear anywhere in a simple-command +or may precede or follow a +.I command\^ +and are +.I not\^ +passed on to the invoked command. +Command and parameter substitution occurs before +.I word\^ +or +.I digit\^ +is used except as noted below. +File name generation +occurs only if the pattern matches a single file +and blank interpretation is not performed. +.TP 14 +.BI < word +Use file +.I word\^ +as standard input (file descriptor 0). +.TP +.BI > word +Use file +.I word\^ +as standard output (file descriptor 1). +If the file does not exist then it is created; +otherwise, it is truncated to zero length. +.TP +.BI >\h@-.3m@> word +Use file +.I word\^ +as standard output. +If the file exists then output is appended to it (by first seeking to the end-of-file); +otherwise, the file is created. +.TP +\f3<\h@-.3m@<\fP\*(OK\f3\-\fP\*(CK\f2word\fP +The shell input is read up to a line that is the same as +.IR word , +or to an end-of-file. +No parameter substitution, command substitution or +file name generation is performed on +.IR word . +The resulting document, +called a +.IR here-document , +becomes +the standard input. +If any character of +.I word\^ +is quoted, then no interpretation +is placed upon the characters of the document; +otherwise, parameter and command substitution occurs, +.B \enew-line +is ignored, +and +.B \e +must be used to quote the characters +.BR \e , +.BR $ , +.BR \*` , +and the first character of +.IR word . +If +.B \- +is appended to +.BR <\h@-.3m@< , +then all leading tabs are stripped from +.I word\^ +and from the document. +.TP +.BI <& digit +The standard input is duplicated from file descriptor +.I digit +(see +.IR dup (2)). +Similarly for the standard output using +.BR >& +.IR digit . +.TP +.B <&\- +The standard input is closed. +Similarly for the standard output using +.BR >&\- . +.PP +If one of the above is preceded by a digit, +then the +file descriptor number referred to is that specified +by the digit +(instead of the default 0 or 1). +For example: +.RS +.PP +\&.\|.\|. \|2>&1 +.RE +.PP +means file descriptor 2 is to be opened +for writing as a duplicate +of file descriptor 1. +.PP +The order in which redirections are specified is significant. +The shell evaluates each redirection in terms of the +.RI ( "file descriptor" ", " file ) +association at the time of evaluation. +For example: +.RS +.PP +\&.\|.\|. \|1>\f2fname\^\fP 2>&1 +.RE +.PP +first associates file descriptor 1 with file +.IR fname\^ . +It then associates file descriptor 2 with the file associated with file +descriptor 1 (i.e. +.IR fname\^ ). +If the order of redirections were reversed, file descriptor 2 would be associated +with the terminal (assuming file descriptor 1 had been) and then file descriptor +1 would be associated with file +.IR fname\^ . +.PP +If a command is followed by +.B & +and job control is not active, +then the default standard input +for the command +is the empty file +.BR /dev/null . +Otherwise, the environment for the execution of a command contains the +file descriptors of the invoking shell as modified by +input/output specifications. +.SS Environment. +The +.I environment\^ +(see +.IR environ (7)) +is a list of name-value pairs that is passed to +an executed program in the same way as a normal argument list. +The names must be +.I identifiers\^ +and the values are character strings. +The shell interacts with the environment in several ways. +On invocation, the shell scans the environment +and creates a +parameter +for each name found, +giving it the corresponding value and marking it +.I export . +Executed commands inherit the environment. +If the user modifies the values of these +parameters +or creates new ones, +using the +.B export +or +.B typeset \-x +commands they become part of the +environment. +The environment seen by any executed command is thus composed +of any name-value pairs originally inherited by the shell, +whose values may be modified by the current shell, +plus any additions +which must be noted in +.B export +or +.B typeset \-x +commands. +.PP +The environment for any +.I simple-command\^ +or function +may be augmented by prefixing it with one or more parameter assignments. +A parameter assignment argument is a word of the form +.IR identifier=value . +Thus: +.RS +.PP +\s-1TERM\s+1=450 \|cmd \|args and +.br +(export \|\s-1TERM\s+1; \|\s-1TERM\s+1=450; \|cmd \|args) +.RE +.PP +are equivalent (as far as the above execution of +.I cmd\^ +is concerned). +.PP +If the +.B \-k +flag is set, +.I all\^ +parameter assignment arguments are placed in the environment, +even if they occur after the command name. +The following +first prints +.B "a=b c" +and then +.BR c: +.PP +.RS +.nf +echo \|a=b \|c +set \|\-k +echo \|a=b \|c +.fi +.RE +.SS Functions. +.PP +The +.B function\^ +keyword, described in the +.I Commands +section above, +is used to define shell functions. +Shell functions are read in and stored internally. +Alias names are resolved when the function is read. +Functions are executed like commands with the arguments +passed as positional parameters. +(See +.I Execution +below). +.PP +Functions execute in the same process as the caller and +share all files, traps ( other than +.SM +.B EXIT +and +.SM +.BR ERR ) +and present working directory with the +caller. +A trap set on +.SM +.B EXIT +inside a function +is executed after the function completes. +Ordinarily, +variables are shared between the calling program +and the function. +However, +the +.B typeset +special command used within a function +defines local variables whose scope includes +the current function and +all functions it calls. +.PP +The special command +.B return +is used to return +from function calls. +Errors within functions return control to the caller. +.PP +Function identifiers +can be listed with the +.B \-f +option of the +.B typeset +special command. +The text of functions will also +be listed. +Function can be undefined with the +.B \-f +option of the +.B unset +special command. +.PP +Ordinarily, +functions are unset when the shell executes a shell script. +The +.B \-xf +option of the +.B typeset +command allows a function to be exported +to scripts that are executed without a separate +invocation of the shell. +Functions that need to be defined across separate +invocations of the shell should be placed in the +.B +.SM +ENV +file. +.SS Jobs. +.PP +If the +.B monitor +option of the +.B set +command is turned on, +an interactive shell associates a \fIjob\fR with each pipeline. It keeps +a table of current jobs, printed by the +.B jobs +command, and assigns them small integer numbers. When +a job is started asynchronously with +.BR & , +the shell prints a line which looks +like: +.PP +.DT + [1] 1234 +.PP +indicating that the job which was started asynchronously was job number +1 and had one (top-level) process, whose process id was 1234. +.PP +This paragraph and the next require features that are +not in all versions of UNIX and may not apply. +If you are running a job and wish to do something else you may hit the key +\fB^Z\fR (control-Z) which sends a STOP signal to the current job. +The shell will then normally indicate that the job has been `Stopped', +and print another prompt. You can then manipulate the state of this job, +putting it in the background with the +.B bg +command, or run some other +commands and then eventually bring the job back into the foreground with +the foreground command +.BR fg . +A \fB^Z\fR takes effect immediately and +is like an interrupt in that pending output and unread input are discarded +when it is typed. +.PP +A job being run in the background will stop if it tries to read +from the terminal. Background jobs are normally allowed to produce output, +but this can be disabled by giving the command ``stty tostop''. +If you set this +tty option, then background jobs will stop when they try to produce +output like they do when they try to read input. +.PP +There are several ways to refer to jobs in the shell. The character +.B % +introduces a job name. If you wish to refer to job number 1, you can +name it as +.B %1 . +Jobs can also be named by prefixes of the string typed in to +.B kill +or restart them. +Thus, on systems that support job control, +.RB ` fg +.BR %ed ' +would normally restart +a suspended +.IR ed (1) +job, if there were a suspended job whose name began with +the string `ed'. +.PP +The shell maintains a notion of the current and previous jobs. +In output pertaining to jobs, the current job is marked with a +.B + +and the previous job with a +.BR \- . +The abbreviation +.B %+ +refers +to the current job and +.B %\- +refers to the previous job. +.B %% +is also a synonym for the current job. +.PP +This shell learns immediately whenever a process changes state. +It normally informs you whenever a job becomes blocked so that +no further progress is possible, but only just before it prints +a prompt. This is done so that it does not otherwise disturb your work. +.PP +When you try to leave the shell while jobs are running or stopped, you will +be warned that `You have stopped(running) jobs.' You may use the +.B jobs +command to see what they are. If you do this or immediately try to +exit again, the shell will not warn you a second time, and the stopped +jobs will be terminated. +.SS Signals. +The \s-1INT\s+1 and \s-1QUIT\s+1 signals for an invoked +command are ignored if the command is followed by +.B & +and job +.B monitor +option is not active. +Otherwise, signals have the values +inherited by the shell from its parent, +with the exception of signal 11 +(but see also +the +.B trap +command below). +.SS Execution. +Each time a command is executed, the above substitutions +are carried out. +If the command name matches one +of the +.I "Special Commands\^" +listed below, +it is executed within the +current shell process. +Next, the command name is checked to see if +it matches one of the user defined functions. +If it does, +the positional parameters are saved +and then reset to the arguments of the +.I function\^ +call. +When the +.I function\^ +completes or issues a +.BR return , +the positional parameter list is restored +and any trap set on +.SM +.B EXIT +within the function is executed. +The value of a +.I function\^ +is the value of the last command executed. +A function is also executed in the +current shell process. +If a command name is not a +.I "special command\^" +or a user defined +.IR function , +a process is created and +an attempt is made to execute the command via +.IR exec (2). +.PP +The shell parameter +.B +.SM PATH +defines the search path for +the directory containing the command. +Alternative directory names are separated by +a colon +.RB ( : ). +The default path is +.B :/bin:/usr/bin +(specifying the current directory, +.BR /bin , +and +.BR /usr/bin , +in that order). +Note that the current directory +is specified by a null path name, +which can appear immediately after the +equal sign, between colon delimiters, +or at the end of the path list. +If the command name contains a \f3/\fP then the search path +is not used. +Otherwise, each directory in the path is +searched for an executable file. +If the file has execute permission but is not a +directory or an +.B a.out +file, +it is assumed to be a file containing shell commands. +A sub-shell is spawned to read it. +All non-exported aliases, +functions, +and named parameters are removed in this case. +A parenthesized command is also executed in +a sub-shell. +.SS Command Re-entry. +The text of the last +.B +.SM +HISTSIZE +(default 128) +commands entered from a terminal device +is saved in a +.I history +file. +The file +.B \s-1$HOME\s+1/.history +is used if the +.B +.SM +HISTFILE +variable is not set +or is not writable. +A shell can access the commands of +all +.I interactive +shells which use the same named +.SM +.BR HISTFILE . +The special command +.B fc\^ +is used to list or +edit a portion this file. +The portion of the file to be edited or listed can be selected by +number or by giving the first character or +characters of the command. +A single command or range of commands can be specified. +If you do not specify an editor program as +an argument to +.B fc\^ +then the value of the parameter +.SM +.B FCEDIT +is used. +If +.SM +.B FCEDIT +is not defined then +.I /bin/ed +is used. +The edited command(s) is printed and re-executed upon +leaving the editor. +The editor name +.B \- +is used to skip the editing phase and +to re-execute the command. +In this case a substitution parameter of the form +\f2old\fP\f3=\fP\f2new\fP +can be used to modify the command before execution. +For example, if +.B r +is aliased to +.B \(fmfc \-e \-\(fm +then typing +`\f3r bad=good c\fP' +will re-execute the most recent command which starts with the letter +.BR c , +replacing the string +.B bad +with the string +.BR good . +.SS In-line Editing Options +Normally, each command line entered from a terminal device is simply +typed followed by a new-line (`RETURN' or `LINE\ FEED'). +If either the +.IR emacs , +.IR gmacs , +or +.I vi +option is active, the user can edit the command line. +To be in either of these edit modes +.B set +the corresponding +option. +An editing option is automatically selected each time the +.SM +.B VISUAL +or +.SM +.B EDITOR +variable is assigned a value ending in either of these +option names. +.PP +The editing features require that the user's terminal +accept `RETURN' as carriage return without line feed +and that a space (`\ ' must overwrite the current character on +the screen. +ADM terminal users should set the "space\ -\ advance" +switch to `space'. +Hewlett-Packard series 2621 terminal users should set the straps to +`bcGHxZ\ etX'. +.PP +The editing modes implement a concept where the user is looking through a +window at the current line. +The window width is the value of +.SM +.B COLUMNS +if it is defined, otherwise 80. +If the line is longer than the window width minus two, a mark is +displayed at the end of the window to notify the user. +As the cursor moves and reaches the window boundaries the window will be +centered about the cursor. +The mark is a +.BR > " (" +.BR < ", " +.BR * ) +if the line extends on the +right (left, both) side(s) of the window. +.SS Emacs Editing Mode +This mode is entered by enabling either the +.I emacs +or +.I gmacs +option. +The only difference between these two modes is the way +they handle +.BR ^T . +To edit, the user +moves the cursor to the point needing correction and +then inserts or deletes characters or words as needed. +All the editing commands are control characters or escape +sequences. +The notation for control characters is caret ( +.B ^ +) followed +by the character. +For example, +.B ^F +is the notation for control +.BR F . +This is entered by depressing `f' while holding down the +`CTRL' (control) key. +The `SHIFT' key is +.I not +depressed. +(The notation +.B ^? +indicates the DEL (delete) key.) +.PP +The notation for escape sequences is +.B M- +followed by a +character. +For example, +.B M-f +(pronounced Meta f) +is entered by depressing ESC +(ascii +.B 033 +) +followed by `f'. +( +.B M-F +would be the notation for ESC followed by `SHIFT' (capital) `F'.) +.PP +All edit commands +operate from any place on the line +(not just at the beginning). +Neither the "RETURN" nor the "LINE FEED" key is +entered after edit commands except when noted. +.PP +.PD 0 +.TP 10 +.BI ^F +Move cursor forward (right) one character. +.PP +.TP 10 +.BI M-f +Move cursor forward one word. +(The editor's idea of a word is a string of characters +consisting of only letters, digits and underscores.) +.PP +.TP 10 +.BI ^B +Move cursor backward (left) one character. +.PP +.TP 10 +.BI M-b +Move cursor backward one word. +.PP +.TP 10 +.BI ^A +Move cursor to start of line. +.PP +.TP 10 +.BI ^E +Move cursor to end of line. +.PP +.TP 10 +.BI ^] char +Move cursor to character +.I char +on current line. +.PP +.TP 10 +.BI ^X^X +Interchange the cursor and mark. +.PP +.TP 10 +.I erase +(User defined erase character as defined +by the stty command, usually +.B ^H +or +.BR # .) +Delete previous character. +.PP +.TP 10 +.BI ^D +Delete current character. +.PP +.TP 10 +.BI M-d +Delete current word. +.PP +.TP 10 +.BI M-^H +(Meta-backspace) Delete previous word. +.PP +.TP 10 +.BI M-h +Delete previous word. +.PP +.TP 10 +.BI M-^? +(Meta-DEL) Delete previous word (if your interrupt character is +.B ^? +(DEL, the default) then this command will not work). +.PP +.TP 10 +.BI ^T +Transpose current character with next character in +.I emacs +mode. +Transpose two previous characters in +.I gmacs +mode. +.PP +.TP 10 +.BI ^C +Capitalize current character. +.PP +.TP 10 +.BI M-C +Capitalize current word. +.PP +.TP 10 +.BI ^K +Kill from the cursor to the end of the line. +If given a parameter of zero then kill from +the start of line to the cursor. +.PP +.TP 10 +.BI ^W +Kill from the cursor to the mark. +.PP +.TP 10 +.BI M-p +Push the region from the cursor to the mark on the stack. +.PP +.TP 10 +.I kill +(User defined kill character as defined +by the stty command, usually +.B ^G +or +.BR @ .) +Kill the entire current line. +If two +.I kill +characters are entered in succession, all +kill characters from then on cause a line feed +(useful when using paper terminals). +.PP +.TP 10 +.BI ^Y +Restore last item removed from line. (Yank item back to the line.) +.PP +.TP 10 +.BI ^L +Line feed and print current line. +.PP +.TP 10 +.BI ^@ +(Null character) Set mark. +.PP +.TP 10 +.BI M- +(Meta space) Set mark. +.PP +.TP 10 +.BI ^J +(New\ line) Execute the current line. +.PP +.TP 10 +.BI ^M +(Return) Execute the current line. +.PP +.TP 10 +.I eof +End-of-file character, +normally +.BR ^D , +will terminate the shell +if the current line is null. +.PP +.TP 10 +.BI ^P +Fetch previous command. +Each time +.B ^P +is entered +the previous command back in time is accessed. +.PP +.TP 10 +.BI M-< +Fetch the least recent (oldest) history line. +.PP +.TP 10 +.BI M-> +Fetch the most recent (youngest) history line. +.PP +.TP 10 +.BI ^N +Fetch next command. +Each time +.B ^N +is entered +the next command forward in time is accessed. +.PP +.TP 10 +.BI ^R string +Reverse search history for a previous command line containing +.IR string . +If a parameter of zero is given the search is forward. +.I String +is terminated by a "RETURN" or "NEW\ LINE". +.PP +.TP 10 +.B ^O +Operate \- Execute the current line and fetch +the next line relative to current line from the +history file. +.PP +.TP 10 +.BI M- digits +(Escape) Define numeric parameter, the digits +are taken as a parameter to the next command. +The commands that accept a parameter are +.BR ^F , +.BR ^B , +.IR erase , +.BR ^D , +.BR ^K , +.BR ^R , +.B ^P +and +.BR ^N . +.PP +.TP 10 +.BI M- letter +Soft-key \- Your alias list is searched for an +alias by the name +.BI _ letter +and if an alias of this name is defined, its +value will be inserted on the line. +The +.I letter +must not be one of the above meta-functions. +.PP +.TP 10 +.B M-_ +The last parameter of the previous command is inserted +on the line. +.PP +.TP 10 +.B M-. +The last parameter of the previous command is inserted +on the line. +.PP +.TP 10 +.B M-* +Attempt file name generation on the current word. +.PP +.TP 10 +.BI ^U +Multiply parameter of next command by 4. +.PP +.TP 10 +.BI \e +Escape next character. +Editing characters, the user's erase, kill and +interrupt (normally +.B ^? +) +characters +may be entered +in a command line or in a search string if preceded by a +.BR \e . +The +.B \e +removes the next character's +editing features (if any). +.PP +.TP 10 +.BI ^V +Display version of the shell. +.PD +.SS Vi Editing Mode +There are two typing modes. +Initially, when you enter a command you are in the +.I input\^ +mode. +To edit, the user enters +.I control\^ +mode by typing ESC ( +.B 033 +) and +moves the cursor to the point needing correction and +then inserts or deletes characters or words as needed. +Most control commands accept an optional repeat +.I count +prior to the command. +.P +When in vi mode on most systems, +canonical processing is initially enabled and the +command will be echoed again if the speed is 1200 baud or greater and it +contains any control characters or less than one second has elapsed +since the prompt was printed. +The ESC character terminates canonical processing for the remainder of the command +and the user can than modify the command line. +This scheme has the advantages of canonical processing with the type-ahead +echoing of raw mode. +.P +If the option +.B viraw\^ +is also set, the terminal will always have canonical processing +disabled. This mode is implicit for systems that do not support two +alternate end of line delimiters, +and may be helpful for certain terminals. +.SS "\ \ \ \ \ Input Edit Commands" +.PP +.RS +By default the editor is in input mode. +.PD 0 +.TP 10 +.I erase +(User defined erase character as defined +by the stty command, usually +.B ^H +or +.BR # .) +Delete previous character. +.TP 10 +.BI ^W +Delete the previous blank separated word. +.TP 10 +.BI ^D +Terminate the shell. +.TP 10 +.BI ^V +Escape next character. +Editing characters, the user's erase or kill +characters may be entered +in a command line or in a search string if preceded by a +.BR ^V . +The +.B ^V +removes the next character's +editing features (if any). +.TP 10 +.BI \e +Escape the next +.I erase +or +.I kill +character. +.P +.RE +.SS "\ \ \ \ \ Motion Edit Commands" +.RS +These commands will move the cursor. +.TP 10 +[\f2count\fP]\f3l\fP +Cursor forward (right) one character. +.TP 10 +[\f2count\fP]\f3w\fP +Cursor forward one alpha-numeric word. +.TP 10 +[\f2count\fP]\f3W\fP +Cursor to the beginning of the next word that follows a blank. +.TP 10 +[\f2count\fP]\f3e\fP +Cursor to end of word. +.TP 10 +[\f2count\fP]\f3E\fP +Cursor to end of the current blank delimited word. +.TP 10 +[\f2count\fP]\f3h\fP +Cursor backward (left) one character. +.TP 10 +[\f2count\fP]\f3b\fP +Cursor backward one word. +.TP 10 +[\f2count\fP]\f3B\fP +Cursor to preceding blank separated word. +.TP 10 +[\f2count\fP]\f3f\fP\f2c\fP +Find the next character \fIc\fP in the current line. +.TP 10 +[\f2count\fP]\f3F\fP\f2c\fP +Find the previous character \fIc\fP in the current line. +.TP 10 +[\f2count\fP]\f3t\fP\f2c\fP +Equivalent to +.B f +followed by +.BR h . +.TP 10 +[\f2count\fP]\f3T\fP\f2c\fP +Equivalent to +.B F +followed by +.BR l . +.TP 10 +.B ; +Repeats the last single character find command, +.BR f , +.BR F , +.BR t , +or +.BR T . +.TP 10 +.B , +Reverses the last single character find command. +.TP 10 +.B 0 +Cursor to start of line. +.TP 10 +.B ^ +Cursor to first non-blank character in line. +.TP 10 +.B $ +Cursor to end of line. +.RE +.SS "\ \ \ \ \ Search Edit Commands" +.RS +These commands access your command history. +.TP 10 +[\f2count\fP]\f3k\fP +Fetch previous command. +Each time +.B k +is entered +the previous command back in time is accessed. +.TP 10 +[\f2count\fP]\f3\-\fP +Equivalent to +.BR k . +.TP 10 +[\f2count\fP]\f3j\fP +Fetch next command. +Each time +.B j +is entered +the next command forward in time is accessed. +.TP 10 +[\f2count\fP]\f3+\fP +Equivalent to +.BR j . +.TP 10 +[\f2count\fP]\f3G\fP +The command number +.I count +is fetched. +The default is the least recent history command. +.TP 10 +.BI / string +Search backward through history for a previous command containing +.IR string . +.I String +is terminated by a "RETURN" or "NEW\ LINE". +If \fIstring\fP is null the previous string will be used. +.TP 10 +.BI ? string +Same as +.B / +except that search will be in the forward direction. +.TP 10 +.B n +Search for next match of the last pattern to +.B / +or +.B ? +commands. +.TP 10 +.B N +Search for next match of the last pattern to +.B / +or +.BR ? , +but in reverse direction. +Search history for the \fIstring\fP entered by the previous \fB/\fP command. +.RE +.SS "\ \ \ \ \ Text Modification Edit Commands" +.RS +These commands will modify the line. +.TP 10 +.B a +Enter input mode and enter text after the current character. +.TP 10 +.B A +Append text to the end of the line. Equivalent to +.BR $a . +.TP 10 +[\f2count\fP]\f3c\fP\f2motion\fP +.TP 10 +\f3c\fP[\f2count\fP]\f2motion\fP +Delete current character through the character +.I motion +moves the cursor to and enter input mode. +If \fImotion\fP is +.BR c , +the entire line will be deleted and +input mode entered. +.TP 10 +.B C +Delete the current character through the end of line and enter input mode. +Equivalent to +.BR c$ . +.TP 10 +.B S +Equivalent to +.BR cc . +.TP 10 +.B D +Delete the current character through the end of line. +.TP 10 +[\f2count\fP]\f3d\fP\f2motion\fP +.TP 10 +\f3d\fP[\f2count\fP]\f2motion\fP +Delete current character through the character +.I motion +moves the cursor to. Equivalent to +.BR d$ . +If \fImotion\fP is +.B d , +the entire line will be deleted. +.TP 10 +.B i +Enter input mode and insert text before the current character. +.TP 10 +.B I +Insert text before the beginning of the line. Equivalent to +the two character sequence +.BR ^i . +.TP 10 +[\f2count\fP]\f3P\fP +Place the previous text modification before the cursor. +.TP 10 +[\f2count\fP]\f3p\fP +Place the previous text modification after the cursor. +.TP 10 +.B R +Enter input mode and +replace characters on the screen with characters you type overlay fashion. +.TP 10 +.BI r c +Replace the current character with +.IR c . +.TP 10 +[\f2count\fP]\f3x\fP +Delete current character. +.TP 10 +[\f2count\fP]\f3X\fP +Delete preceding character. +.TP 10 +[\f2count\fP]\f3.\fP +Repeat the previous text modification command. +.TP 10 +.B \(ap +Invert the case of the current character and advance the cursor. +.TP 10 +[\f2count\fP]\f3_\fP +Causes the +.I count\^ +word of the previous command to be appended and +input mode entered. +The last word is used +if +.I count\^ +is omitted. +.TP 10 +.B * +Causes an +.B * +to be appended to the current word and file name generation attempted. +If no match is found, +it rings the bell. Otherwise, the word is replaced +by the matching pattern and input mode is entered. +.RE +.SS "\ \ \ \ \ Other Edit Commands" +.RS +Miscellaneous commands. +.TP 10 +.B u +Undo the last text modifying command. +.TP 10 +.B U +Undo all the text modifying commands performed on the line. +.TP 10 +[\f2count\fP]\f3v\fP +Returns the command +.BI "fc \-e ${\s-1VISUAL\s+1:\-${\s-1EDITOR\s+1:\-vi}}" " count" +in the input buffer. +If +.I count\^ +is omitted, then the current line is used. +.TP 10 +.BI ^L +Line feed and print current line. +Has effect only in control mode. +.TP 10 +.BI ^J +(New\ line) Execute the current line, regardless of mode. +.TP 10 +.BI ^M +(Return) Execute the current line, regardless of mode. +.TP 10 +.B \# +Equivalent to +\f3I#\fP\f2<cr>\fP. +Useful for causing the current line to be +inserted in the history without being executed. +.RE +.PD +.SS Special Commands. +The following simple-commands are executed in the shell process. +Input/Output redirection is permitted. +File descriptor 1 is the default output location. +Parameter assignment lists preceding the command do not +remain in effect when the command completes unless noted. +.TP +\f3:\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK +Parameter assignments remain in effect after the command completes. +The command only expands parameters. +A zero exit code is returned. +.br +.ne 2 +.TP +\f3\|. \f2file\^\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK +Parameter assignments remain in effect after the command completes. +Read and execute commands from +.I file\^ +and return. +The commands are executed in the current Shell environment. +The search path +specified by +.B +.SM PATH +is used to find the directory containing +.IR file . +If any arguments +.I arg\^ +are given, +they become the positional parameters. +Otherwise the positional parameters are unchanged. +.TP +\f3alias\fP \*(OK \f3\-tx\fP \*(CK \*(OK \f2name\fP\*(OK \f2=value\^\fP \*(CK .\|.\|. \*(CK +.I Alias\^ +with no arguments prints the list of aliases +in the form +.I name=value\^ +on standard output. +An +.I alias\^ +is defined +for each name whose +.I value\^ +is given. +A trailing space in +.I value\^ +causes the next word to be checked for +alias substitution. +The +.B \-t +flag is used to set and list tracked aliases. +The value of a tracked alias is the full pathname +corresponding to the given +.IR name . +The value becomes undefined when the value of +.SM +.B PATH +is reset but the aliases remained tracked. +Without the +.B \-t +flag, +for each +.I name\^ +in the argument list +for which no +.I value\^ +is given, the name +and value of the alias is printed. +The +.B \-x +flag is used to set or print exported aliases. +An exported alias is defined across sub-shell environments. +Alias returns true unless a +.I name\^ +is given for which no alias has been defined. +.TP +\f3bg\fP \*(OK \f3%\f2job\^\fP \*(CK +This command is only built-in on systems that support job control. +Puts the specified +.I job\^ +into the background. +The current job is put in the background +if +.I job\^ +is not specified. +.TP +\f3break\fP \*(OK \f2n\^\fP \*(CK +Exit from the enclosing +.BR for +.BR while +.BR until +or +.B select\^ +loop, if any. +If +.I n\^ +is specified then break +.I n\^ +levels. +.TP +\f3continue\fP \*(OK \f2n\^\fP \*(CK +Resume the next iteration of the enclosing +.BR for +.BR while +.BR until +or +.B select\^ +loop. +If +.I n\^ +is specified then resume at the +.IR n -th +enclosing loop. +.TP +.PD 0 +\f3cd\fP \*(OK \f2arg\^\fP \*(CK +.TP +\f3cd\fP \f2old\^\fP \f2new\^\fP +.PD +This command can be in either of two forms. +In the first form it +changes the current directory to +.IR arg . +If +.I arg\^ +is +.B \- +the directory is changed to the previous +directory. +The shell +parameter +.B +.SM HOME +is the default +.IR arg . +The parameter +.SM +.B PWD +is set to the current directory. +The shell parameter +.B +.SM CDPATH +defines the search path for +the directory containing +.IR arg . +Alternative directory names are separated by +a colon +.RB ( : ). +The default path is +.B <null> +(specifying the current directory). +Note that the current directory is specified by a null path name, +which can appear immediately after the equal sign +or between the colon delimiters anywhere else in the path list. +If +.I arg +begins with a \f3/\fP then the search path +is not used. +Otherwise, each directory in the path is +searched for +.IR arg . +.P +The second form of +.B cd +substitutes the string +.I new +for the string +.I old +in the current directory name, +.SM +.B PWD +and tries to change to this new directory. +.P +The +.B cd\^ +command may not be executed by +.I rsh\^. +.TP +\f3eval\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK +The arguments are read as input +to the shell +and the resulting command(s) executed. +.TP +\f3exec\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK +Parameter assignments remain in effect after the command completes. +If +.I arg\^ +is given, +the command specified by +the arguments is executed in place of this shell +without creating a new process. +Input/output arguments may appear and +affect the current process. +If no +arguments are given +the effect of this command is to +modify file descriptors +as prescribed by the input/output redirection list. +In this case, +any file descriptor numbers greater than 2 that are +opened with this mechanism are closed when invoking +another program. +.TP +\f3exit\fP \*(OK \f2n\^\fP \*(CK +Causes the shell to exit +with the exit status specified by +.IR n . +If +.I n\^ +is omitted then the exit status is that of the last command executed. +An end-of-file will also cause the shell to exit +except for a +shell which has the +.I ignoreeof +option (See +.B set +below) turned on. +.TP +\f3export\fP \*(OK \f2name\^\fP .\|.\|. \*(CK +The given +.IR name s +are marked for automatic +export to the +.I environment\^ +of subsequently-executed commands. +.TP +.PD 0 +\f3fc\fP \*(OK \f3\-e \f2ename\^\fP \ \*(CK \*(OK \f3\-\f3nlr\^\f1 \*(CK \*(OK \f2first\^\fP \*(CK \*(OK \f2last\^\fP \*(CK +.TP +\f3fc \-e \-\fP \*(OK \f2old\fP\f3\=\fP\f2new\^\fP \*(CK \*(OK \f2command\^\fP \*(CK +.PD +In the first form, +a range of commands from +.I first\^ +to +.I last\^ +is selected from the last +.SM +.B HISTSIZE +commands that were typed at the terminal. +The arguments +.I first\^ +and +.I last\^ +may be specified as a number or as a string. +A string is used to locate the most recent command starting with +the given string. +A negative number is used as an offset to the current command number. +If the flag +.BR \-l , +is selected, +the commands are listed on standard output. +Otherwise, the editor program +.I ename\^ +is invoked on a file containing these +keyboard commands. +If +.I ename\^ +is not supplied, then the value of the parameter +.SM +.B FCEDIT +(default /bin/ed) +is used as the editor. +When editing is complete, the edited command(s) +is executed. +.I last\^ +is not specified +then it will be set to +.IR first . +If +.I first\^ +is not specified +the default is the previous command +for editing and \-16 for listing. +The flag +.B \-r +reverses the order of the commands and +the flag +.B \-n +suppresses command numbers when listing. +In the second form the +.I command\^ +is re-executed after the substitution +\f2old\^\fP\f3=\fP\f2new\^\fP +is performed. +.TP +\f3fg\fP \*(OK \f3%\f2job\^\fP \*(CK +This command is only built-in on systems that support job control. +If +.I job\^ +is specified it brings it to the foreground. +Otherwise, the current job is +brought into the foreground. +.TP +\f3jobs\fP \*(OK \f3\-l\^\fP \*(CK +Lists the active jobs; given the +.B \-l +options lists process id's in addition to the normal information. +.TP +\f3kill\fP \*(OK \f3\-\f2sig\^\fP \*(CK \f2process\^\fP .\|.\|. +Sends either the TERM (terminate) signal or the +specified signal to the specified jobs or processes. +Signals are either given by number or by names (as given in +.I /usr/include/signal.h, +stripped of the prefix ``SIG''). +The signal names are listed by +.BR "kill \-l'" . +There is no default, saying just `kill' does not +send a signal to the current job. +If the signal being sent is TERM (terminate) or HUP (hangup), +then the job or process will be sent a CONT (continue) signal +if it is stopped. +The argument +.I process\^ +can be either a process id or a job. +.TP +\f3let\fP \f2arg\^\fP .\|.\|. +Each +.I arg +is an +.IR "arithmetic expression" +to be evaluated. +All calculations are done as long +integers and no check for overflow +is performed. +Expressions consist of constants, +named parameters, and operators. +The following set of operators, +listed in order of decreasing precedence, +have been implemented: +.RS +.PD 0 +.TP +.B \- +unary minus +.TP +.B ! +logical negation +.TP +.B "* / %" +.br +multiplication, division, remainder +.TP +.B "+ \-" +addition, subtraction +.TP +.B "<= >= < >" +.br +comparison +.TP +.B "== !=" +.br +equality inequality +.TP +.B = +arithmetic replacement +.PD +.PP +Sub-expressions in parentheses +.B (\|) +are evaluated first and can be used +to override the above precedence rules. +The evaluation within a precedence group +is from right to left for the +.B = +operator +and from left to right for the others. +.PP +A parameter name must be a valid +.IR identifier . +When a parameter is encountered, +the value associated with the +parameter name is substituted and expression evaluation resumes. +Up to nine levels of recursion are +permitted. +.PP +The return code is +0 if the value of the last expression +is non-zero, and 1 otherwise. +.RE +.TP +\f3newgrp\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK +Equivalent to +.BI "exec newgrp" " arg\^" +\&.\|.\|.\^. +.TP +\f3print\fP \*(OK \f3\-Rnprsu\^\fP\*(OK\f2n\fP \*(CK \*(CK \*(OK \f2arg\^\fP .\|.\|. \*(CK +The shell output mechanism. +With no flags or with flag +.BR \- , +the arguments are printed +on standard output as described by +.IR echo (1). +In raw mode, +.B \-R +or +.BR \-r , +the escape conventions of +.I echo +are ignored. +The +.B \-R +option will print all subsequent arguments and options +other than +.BR \-n . +The +.B \-p +option causes the +arguments to be written onto the pipe +of the process spawned with +.B \(bv& +instead of standard output. +The +.B \-s +option causes the +arguments to be written onto the history file +instead of standard output. +The +.B \-u +flag can be used to specify a one digit +file descriptor unit number +.B n\^ +on which the +output will be placed. +The default is 1. +If the flag +.B \-n +is used, no +.B new-line\^ +is added to the output. +.TP +\f3read\fP \*(OK \f3\-prsu\^\fP\*(OK \f2n\^\fP \*(CK \*(CK \*(OK \f2name\f3?\f2prompt\^\f1 \*(CK \*(OK \f2name\^\fP .\|.\|. \*(CK +The shell input mechanism. +One line is read and +is broken up into words using the characters in +.B +.SM IFS +as separators. +In raw mode, +.B \-r, +a +.B \e +at the end of a line does not signify +line continuation. +The first +word is assigned to the first +.IR name , +the second word +to the second +.IR name , +etc., with leftover words assigned to the last +.IR name . +The +.B \-p +option causes the input line +to be taken from the input pipe +of a process spawned by the shell +using +.BR \(bv& . +If the +.B \-s +fag is present, +the input will be saved as a command in the history file. +The flag +.B \-u +can be used to specify a one digit file +descriptor unit to read from. +The file descriptor can be opened with the +.B exec\^ +special command. +The default value of +.I n\^ +is 0. +If +.IR name +is omitted then +.SM +.B REPLY +is used as the default +.IR name. +The return code is 0 unless an end-of-file is encountered. +An end-of-file with the +.B \-p +option causes cleanup for this process +so that another can be spawned. +If the first argument contains a +.BR ? , +the remainder of this word is used as a +.I prompt\^ +when the shell is interactive. +If the given file descriptor is open for writing +and is a terminal device then the prompt is placed +on this unit. +Otherwise the prompt is issued on file descriptor 2. +The return code is 0 unless an end-of-file is encountered. +.TP +\f3readonly\fP \*(OK \f2name\fP .\|.\|. \*(CK +The given +.IR names +are marked +readonly and these +names cannot be changed +by subsequent assignment. +.TP +\f3return\fP \*(OK \f2n\^\fP \*(CK +Causes a shell +.I function +to return +to the invoking script +with the return status specified by +.IR n . +If +.I n\^ +is omitted then the return status is that of the last command executed. +If +.B return +is invoked while not in a +.I function +then it is the same as an +.BR exit . +.TP +\f3set\fP \*(OK \f3\-aefhkmnostuvx\fP \*(CK \*(OK \f3\-o\fP \f2option\^\fP .\|.\|. \*(CK \*(OK \f2arg\^\fP .\|.\|. \*(CK +The flags for this command have meaning as follows: +.RS +.PD 0 +.TP 8 +.B \-a +All subsequent parameters that are defined are automatically exported. +.TP 8 +.B \-e +If the shell is non-interactive and if a command fails, +execute the +.SM +.B ERR +trap, if set, +and exit immediately. +This mode is disabled while reading profiles. +.TP 8 +.B \-f +Disables file name generation. +.TP 8 +.B \-h +Each command whose name is an +.I identifier\^ +becomes a tracked alias when first encountered. +.TP 8 +.B \-k +All parameter assignment arguments are placed in the environment for a command, +not just those that precede the command name. +.TP 8 +.B \-m +Background jobs will run in a separate process group +and a line will print upon completion. +The exit status of background jobs is reported in a completion message. +On systems with job control, +this flag is turned on automatically for +interactive shells. +.TP 8 +.B \-n +Read commands but do not execute them. +.TP 8 +.B \-o +The following argument can be one of the following option names: +.RS +.TP 8 +.B allexport +Same as +.BR \-a . +.TP 8 +.B errexit +Same as +.BR \-e . +.TP 8 +.B emacs +Puts you in an +.I emacs +style in-line editor for command entry. +.TP 8 +.B gmacs +Puts you in a +.I gmacs +style in-line editor for command entry. +.TP 8 +.B ignoreeof +The shell will not exit on end-of-file. +The command +.B exit +must be used. +.TP 8 +.B keyword +Same as +.BR \-k . +.TP 8 +.B markdirs +All directory names resulting from file name generation have a trailing +.B / +appended. +.TP 8 +.B monitor +Same as +.BR \-m . +.TP 8 +.B noexec +Same as +.BR \-n . +.TP 8 +.B noglob +Same as +.BR \-f . +.TP 8 +.B nounset +Same as +.BR \-u . +.TP 8 +.B verbose +Same as +.BR \-v . +.TP 8 +.B trackall +Same as +.BR \-h . +.TP 8 +.B vi +Puts you in insert mode of a +.I vi\^ +style in-line editor +until you hit escape character +.BR 033 . +This puts you in move mode. +A return sends the line. +.TP 8 +.B viraw +Each character is processed as it is typed +in +.I vi\^ +mode. +.TP 8 +.B xtrace +Same as +.BR \-x . +.TP 8 + +If no option name is supplied then the current option settings are printed. +.RE +.TP 8 +.B \-s +Sort the positional parameters. +.TP 8 +.B \-t +Exit after reading and executing one command. +.TP 8 +.B \-u +Treat unset parameters as an error when substituting. +.TP 8 +.B \-v +Print shell input lines as they are read. +.TP 8 +.B \-x +Print commands and their arguments as they are executed. +.TP 8 +.B \- +Turns off +.B \-x +and +.B \-v +flags and stops examining arguments for flags. +.TP 8 +.B \-\- +Do not change any of the flags; useful in setting +.B $1 +to a value beginning with +.BR \- . +If no arguments follow this flag then the positional parameters are unset. +.PD +.PP +Using +.B \+ +rather than +.B \- +causes these flags to be turned off. +These flags can also be used upon invocation of the shell. +The current set of flags may be found in +.BR $\- . +The remaining arguments are positional +parameters and are assigned, in order, +.if t to\p +.if n to +.BR $1 , +.BR $2 , +\&.\|.\|.\^. +If no arguments are given then the values +of all names are printed on the standard output. +.RE +.TP +\f3shift\fP \*(OK \f2n\^\fP \*(CK +.br +The positional parameters from +\f3$\fP\f2n\fP\f3+1\fP +\&.\|.\|. +are renamed +.B $1 +\&.\|.\|.\^ +, default +.I n\^ +is 1. +The parameter +.I n\^ +can be any arithmetic expression that evaluates to a non-negative +number less than or equal to +.BR $# . +.TP +\f3test\fP \*(OK \f2expr\^\fP \*(CK +.br +Evaluate conditional expression +.IR expr . +See +.IR test (1) +for usage and description. +The arithmetic comparison operators +are not restricted to integers. +They allow any arithmetic expression. +Four additional primitive expressions are allowed: +.RS +.PD 0 +.TP +\f3\-L\fP \f2file\^\fP +True if +.I file\^ +is a symbolic link. +.TP +\f2file1\^\fP \f3\-nt\fP \f2file2\^\fP +True if +.I file1\^ +is newer than +.IR file2 . +.TP +\f2file1\^\fP \f3\-ot\fP \f2file2\^\fP +True if +.I file1\^ +is older than +.IR file2 . +.TP +\f2file1\^\fP \f3\-ef\fP \f2file2\^\fP +True if +.I file1\^ +has the same device and i-node number as +.IR file2 . +.PD +.RE +.TP +\f3times\fP +.br +Print the accumulated user and system times for +the shell and for processes +run from the shell. +.TP +\f3trap\fP \*(OK \f2arg\^\fP \*(CK \*(OK \f2sig\^\fP \*(CK .\|.\|. +.I arg\^ +is a command to be read and executed when the shell +receives signal(s) +.IR sig . +(Note that +.I arg\^ +is scanned once when +the trap is set and once when the trap +is taken.) +Each +.I sig\^ +can be given as a number or as the name of the signal. +Trap commands are executed in order of signal number. +Any attempt to set a trap on a signal that +was ignored on entry to the current shell +is ineffective. +An attempt to trap on signal 11 (memory fault) produces an error. +If +.I arg\^ +is omitted or is +.BR \- , +then all trap(s) +.I sig\^ +are reset +to their original values. +If +.I arg\^ +is the null +string then this signal is ignored by the shell and by the commands +it invokes. +If +.I sig\^ +is +.SM +.B ERR +then +.I arg\^ +will be executed whenever a command has a non-zero exit code. +This trap is not inherited by functions. +If +.I sig\^ +is +.B 0 +or +.SM +.B EXIT +and the +.B trap +statement is executed inside the body of a function, +then the command +.I arg\^ +is executed +after the function completes. +If +.I sig\^ +is +.B 0 +or +.SM +.B EXIT +for a +.B trap +set outside any function +then the command +.I arg\^ +is executed +on exit from the shell. +The +.B trap +command +with no arguments prints a list +of commands associated with each signal number. +.TP +\f3typeset\fP \*(OK \f3\-FLRZefilprtux\^\fP\*(OK\f2n\fP \*(CK \*(OK \f2name\fP\*(OK \f2=value\^\fP \*(CK \^ \*(CK .\|.\|. \*(CK +Parameter assignments remain in effect after the command completes. +When invoked inside a function, +a new instance of the parameter +.I name\^ +is created. +The parameter value and type are restored +when the function completes. +The following list of attributes may be specified: +.RS +.PD 0 +.TP +.B \-F +This flag provides UNIX to host-name file mapping on non-UNIX +machines. +.TP +.B \-L +Left justify and remove leading blanks from +.IR value . +If +.I n +is non-zero it defines the width +of the field, +otherwise it is determined by the width of the value of +first assignment. +When the parameter is assigned to, it is +filled on the right with blanks or truncated, if necessary, to +fit into the field. +Leading zeros are removed if the +.B \-Z +flag is also set. +The +.B \-R +flag is turned off. +.TP +.B \-R +Right justify and fill with leading blanks. +If +.I n +is non-zero it defines the width +of the field, +otherwise it is determined by the width of the value of +first assignment. +The field is left filled with blanks or +truncated from the end if the +parameter is reassigned. +The +.B L +flag is turned off. +.TP +.B \-Z +Right justify and fill with leading zeros if +the first non-blank character is a digit and the +.B \-L +flag has not been set. +If +.I n +is non-zero it defines the width +of the field, +otherwise it is determined by the width of the value of +first assignment. +.TP +.B \-e +Tag the parameter as having an error. +This tag is currently unused by the shell and can be +set or cleared by the user. +.TP +.B \-f +The names refer to function names rather than +parameter names. +No assignments can be made and the only other +valid flag is +.BR \-x . +.TP +.B \-i +Parameter is an integer. +This makes arithmetic faster. +If +.I n +is non-zero it defines the output arithmetic base, +otherwise the first assignment determines the output base. +.TP +.B \-l +All upper-case characters +converted to lower-case. +The upper-case flag, +.B \-u +is turned off. +.TP +.B \-p +The output of this command, if any, is written onto the two-way pipe +.TP +.B \-r +The given +.IR names +are marked +readonly and these +names cannot be changed +by subsequent assignment. +.TP +.B \-t +Tags the named parameters. +Tags are user definable and have no special +meaning to the shell. +.TP +.B \-u +All lower-case characters are converted +to upper-case characters. +The lower-case flag, +.B \-l +is turned off. +.TP +.B \-x +The given +.IR name s +are marked for automatic +export to the +.I environment\^ +of subsequently-executed commands. +.PD +.PP +Using +.B \+ +rather than +.B \- +causes these flags to be turned off. +If no +.I name\^ +arguments are given but flags are specified, +a list of +.I names\^ +(and optionally the +.I values\^ +) +of the +.I parameters\^ +which have these +flags set +is printed. +(Using +.B \+ +rather than +.B \- +keeps the +values to be printed.) +If no +.IR name s +and flags +are given, +the +.I names\^ +and +.I attributes\^ +of all +.I parameters\^ +are printed. +.RE +.TP +\f3ulimit\fP \*(OK \f3\-cdfmpt\fP \*(CK \*(OK \f2n\^\fP \*(CK +.RS +.PD 0 +.TP +.B \-c +imposes a size limit of +.I n\^ +blocks on the size of core dumps +(\s-1BSD\s+1 only). +.TP +.B \-d +imposes a size limit of +.I n\^ +blocks on the size of the data area +(\s-1BSD\s+1 only). +.TP +.B \-f +imposes a size limit of +.I n\^ +blocks on files written by child processes (files of any size may be read). +.TP +.B \-m +imposes a soft limit of +.I n\^ +blocks on the size of physical memory +(\s-1BSD\s+1 only). +.TP +.B \-p +changes the pipe size to +.I n\^ +(\s-1UNIX\s+1/\s-1RT\s+1 only). +.TP +.B \-t +imposes a time limit of +.I n\^ +seconds to be used by each process +(\s-1BSD\s+1 only). +.PD +.PP +If no option is given, +.B \-f +is assumed. +If +.I n\^ +is not given the current limit is printed. +.RE +.TP +\f3umask\fP \*(OK \f2nnn\^\fP \*(CK +The user file-creation mask is set to +.I nnn\^ +(see +.IR umask (2)). +If +.I nnn\^ +is omitted, the current value of the mask is printed. +.TP +\f3unalias\fP \f2name\^\fP .\|.\|. +The +.IR +parameters +given by the list of +.IR name s +are removed from the +.I alias\^ +list. +.TP +\f3unset\fP \*(OK \f3\-f\fP \*(CK \f2name\^\fP .\|.\|. +The parameters given by the list of +.IR name s +are unassigned, +i. e., +their values and attributes are erased. +Readonly variables cannot be unset. +If the flag, +.BR \-f , +is set, then the names refer to +.I function\^ +names. +.TP +\f3wait\fP \*(OK \f2n\^\fP \*(CK +Wait for the specified process and +report its termination status. +If +.I n\^ +is not given then all currently active child processes are waited for. +The return code from this command is that of +the process waited for. +.TP +\f3whence\fP \*(OK \f3\-v\fP \*(CK \f2name\^\fP .\|.\|. +For each +.IR name , +indicate how it +would be interpreted if used as a command name. +.P +The flag, +.BR \-v , +produces a more verbose report. +.SS Invocation. +If the shell is invoked by +.IR exec (2), +and the first character of argument zero +.RB ( $0 ) +is +.BR \- , +then the shell is assumed to be a +.I login +shell and +commands are read from +.B /etc/profile +and then from either +.B .profile +in the current directory or +.BR \s-1$HOME\s+1/.profile , +if either file exists. +Next, commands are read from +the file named by +performing parameter substitution on +the value of the environment parameter +.SM +.B ENV +if the file exists. +Commands are then read as described below; +the following flags are interpreted by the shell +when it is invoked: +.PP +.PD 0 +.TP 10 +.BI \-c "\| string\^" +If the +.B \-c +flag is present then +commands are read from +.IR string . +.TP +.B \-s +If the +.B \-s +flag is present or if no +arguments remain +then commands are read from the standard input. +Shell output, +except for the output of some of the +.I Special commands\^ +listed above, +is written to +file descriptor 2. +.TP +.B \-i +If the +.B \-i +flag is present or +if the shell input and output are attached to a terminal (as told by +.IR gtty (2)) +then this shell is +.IR interactive . +In this case \s-1TERMINATE\s+1 is ignored (so that \f3kill 0\fP +does not kill an interactive shell) and \s-1INTERRUPT\s+1 is caught and ignored +(so that +.B wait +is interruptible). +In all cases, \s-1QUIT\s+1 is ignored by the shell. +.TP +.B \-r +If the +.B \-r +flag is present the shell is a restricted shell. +.PD +.PP +The remaining flags and arguments are described under the +.B set +command above. +.SS Rsh Only. +.I Rsh +is used to set up login names and execution environments whose +capabilities are more controlled than those of the standard shell. +The actions of +.I rsh\^ +are identical to those of +.IR sh , +except that the following are disallowed: +.RS +.PD 0 +.PP +changing directory (see +.IR cd (1)), +.br +setting the value of +.SM +.B SHELL +or +.SM +.BR PATH\*S, +.br +specifying path or +command names containing +.BR / , +.br +redirecting output +.RB ( > +and +.BR >> ). +.PD +.RE +.PP +The restrictions above are enforced +after \f3.profile\fP and the +.SM +.B ENV +files are interpreted. +.PP +When a command to be executed is found to be a shell procedure, +.I rsh\^ +invokes +.I sh\^ +to execute it. +Thus, it is possible to provide to the end-user shell procedures +that have access to the full power of +the standard shell, +while imposing a limited menu of commands; +this scheme assumes that the end-user does not have write and +execute permissions in the same directory. +.PP +The net effect of these rules is that the writer of the +.B .profile +has complete control over user actions, +by performing guaranteed setup actions +and leaving the user in an appropriate directory +(probably +.I not\^ +the login directory). +.PP +The system administrator often sets up a directory +of commands +(i.e., +.BR /usr/rbin ) +that can be safely invoked by +.IR rsh . +Some systems also provide a restricted editor +.IR red . +.SH EXIT STATUS +Errors detected by the shell, such as syntax errors, +cause the shell +to return a non-zero exit status. +If the shell is being used non-interactively +then execution of the shell file is abandoned. +Otherwise, the shell returns the exit status of +the last command executed (see also the +.B exit +command above). +.SH FILES +/etc/passwd +.br +/etc/profile +.br +\s-1$HOME\s+1/\f3.\fPprofile +.br +/tmp/sh\(** +.br +/dev/null +.SH SEE ALSO +cat(1), +cd(1), +echo(1), +emacs(1), +env(1), +gmacs(1), +newgrp(1), +test(1), +umask(1), +vi(1), +dup(2), +exec(2), +fork(2), +gtty(2), +pipe(2), +signal(2), +umask(2), +ulimit(2), +wait(2), +rand(3), +a.out(5), +profile(5), +environ(7). +.SH CAVEATS +.PP +If a command which is a +.I "tracked alias" +is executed, and then a command with the same name is +installed in a directory in the search path before the directory where the +original command was found, the shell will continue to +.I exec\^ +the original command. +Use the +.B \-t +option of the +.B alias\^ +command to correct this situation +.PP +If you move the current directory or one above it, +.B pwd\^ +may not give the correct response. +Use the +.B cd\^ +command with a full path name +to correct this situation. +.PP +Some very old shell scripts contain a +.B ^ +as a synonym for the pipe character +.BR \(bv . |