10564b1175
groff 1.23.0 added .MR to its -man macro package. The NEWS file states
that the inclusion of the macro "was prompted by its introduction to
Plan 9 from User Space's troff in August 2020." From d32deab it seems
that the name for Plan 9 from User Space's implementation was suggested
by groff maintainer G. Brandon Robinson.
Not sure if the intention was to make these definitions compatible, but
it would be nice if they were.
Currently, Plan 9 from User Space's .MR expects its second argument to
be parenthesized. groff's .MR does not. This results in extra
parentheses appearing in manual references when viewing Plan 9 from User
Space's manual pages on a system using groff.
40 lines
693 B
Groff
40 lines
693 B
Groff
.TH DUP 3
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.SH NAME
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dup \- duplicate an open file descriptor
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.SH SYNOPSIS
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.B #include <u.h>
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.br
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.B #include <libc.h>
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.PP
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.B
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int dup(int oldfd, int newfd)
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.SH DESCRIPTION
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Given a file descriptor,
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.IR oldfd ,
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referring to an open file,
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.I dup
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returns a new file descriptor referring to the same file.
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.PP
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If
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.I newfd
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is \-1 the system chooses the lowest available file descriptor.
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Otherwise,
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.I dup
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will use
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.I newfd
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for the new file descriptor
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(closing any old file associated with
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.IR newfd ).
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.SH SOURCE
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.B \*9/src/lib9/dup.c
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.SH DIAGNOSTICS
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Sets
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.IR errstr .
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.SH BUGS
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To avoid name conflicts with the underlying system,
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.I dup
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is a preprocessor macro defined as
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.IR p9dup ;
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see
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.MR intro 3 .
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