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| author | Jacob McDonnell <jacob@jacobmcdonnell.com> | 2026-04-26 16:38:00 -0400 |
|---|---|---|
| committer | Jacob McDonnell <jacob@jacobmcdonnell.com> | 2026-04-26 16:38:00 -0400 |
| commit | 97d5c458cfa039d857301e1ca7d5af3beb37131d (patch) | |
| tree | b460cd850d0537eb71806ba30358840377b27688 /static/plan9-4e/man2/dup.2 | |
| parent | b89dc2331a50c63f8b33272a5c4c61ab98abdaa3 (diff) | |
build: Better Build System
Diffstat (limited to 'static/plan9-4e/man2/dup.2')
| -rw-r--r-- | static/plan9-4e/man2/dup.2 | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/static/plan9-4e/man2/dup.2 b/static/plan9-4e/man2/dup.2 new file mode 100644 index 00000000..cd341410 --- /dev/null +++ b/static/plan9-4e/man2/dup.2 @@ -0,0 +1,42 @@ +.TH DUP 2 +.SH NAME +dup \- duplicate an open file descriptor +.SH SYNOPSIS +.B #include <u.h> +.br +.B #include <libc.h> +.PP +.B +int dup(int oldfd, int newfd) +.SH DESCRIPTION +Given a file descriptor, +.IR oldfd , +referring to an open file, +.I dup +returns a new file descriptor referring to the same file. +.PP +If +.I newfd +is \-1 the system chooses the lowest available file descriptor. +Otherwise, +.I dup +will use +.I newfd +for the new file descriptor +(closing any old file associated with +.IR newfd ). +File descriptors are allocated dynamically, +so to prevent unwarranted growth of the file descriptor table, +.I dup +requires that +.I newfd +be no greater than 20 more than the highest file descriptor ever used by +the program. +.SH SOURCE +.B /sys/src/libc/9syscall +.SH SEE ALSO +.IR intro (2), +.IR dup (3) +.SH DIAGNOSTICS +Sets +.IR errstr . |