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.TH NOSH 8
.CT 1 shell proc_man dirs files
.SH NAME
nosh \- `no-surprise' shell, a sub-standard command interpreter
.SH SYNOPSIS
.B /etc/nosh
[
.I file
]
.PP
.B priv nosh -gunxlp
.I file
.SH DESCRIPTION
.I Nosh
executes commands read from its standard input
or from the named
.IR file .
It has few of the advanced features of
.IR sh (1),
making it more trustable for use in
security administration tasks.
In the second usage,
.I nosh
is endowed with one or more of the licenses
.BR gunxlp ;
see
.IR labtoa (3).
.SS Commands
A
command is either
.I simple
or
.I builtin.
Each command consists of
a sequence of
.I words
separated by white space,
terminated by a new-line character or end of input.
Backslash quoting and sharp commenting are honored.
The first word specifies the name of the command to
be executed.
If the command name matches one of the builtins
listed below it is executed in the shell process.
If the command name matches no
builtin command, it is taken to be the
pathname of an executable file; the name must begin with
.L /
or
.LR . .
A new process is created and an attempt is made to
execute the file via
.IR exec (2)
with an empty environment.
.SS Input-Output Redirection
The standard input is inherited by simple commands.
Simple
.B >
output redirection to named files as in
.IR sh (1)
works only for simple commands, and only for file
descriptors 1 (default) and 2.
.SS Builtin Commands
.PP
.PD 0
.TP
.BI cd " dir
Change the current directory to
.I dir.
.TP
.BI exit " status
Exit with given status, 0 by default.
.TP
.B set +e
.TP
.B set -e
Turn an ignore-error switch on
.RB ( +e ,
default) or off
.RB ( -e ).
.I Nosh
normally ignores nonzero exit status from an executed
command, but exits with that status if
.B -e
is set.
.TP
.B set +x
.TP
.B set -x
Refrain from echoing
.RB ( +x ,
default) or echo
.RB ( -x )
each command as it is executed.
.TP
.BI lmask " licenses command \fR[\fP arg \fR... ]\fP
Run a simple command, allowing licenses
indicated by a nonempty string from the set
.BR gunxlp-
to be inherited from
.I nosh.
Normally no licenses are inherited.
.SS Missing features
Features of
.IR sh (1)
that
.IR nosh
lacks include:
background commands, pipelines, compound commands, most builtins,
multicharacter quotation,
command substitution, parameter substitution, variables, environments,
file name generation, redirection of input, signal traps,
search paths, mail notification,
.BR .profile ,
user specification of prompts.
.SH DIAGNOSTICS
.I Nosh
prints nonzero exit or termination status
of executed commands as octal numbers labeled
.L e=
and
.LR t= ;
see
.IR wait (2).
If invoked with a
.I file
argument, it exits unconditionally for nonzero termination
status or syntax error, and conditionally (under control of
.LR set )
for nonzero exit status.
.PP
.I Nosh
exits immediately if
invoked with more than one argument,
if invoked with an argument with a relative path name,
if invoked by a relative path name, or if invoked
with interrupt or quit signals ignored.
.SH SEE ALSO
.IR sh (1)
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