mirror of https://github.com/mkerrisk/man-pages
103 lines
2.0 KiB
Groff
103 lines
2.0 KiB
Groff
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "COLON" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" colon
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.SH NAME
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colon \- null utility
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.SH SYNOPSIS
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.LP
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\fB:\fP \fB[\fP\fIargument\fP \fB...\fP\fB]\fP
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.SH DESCRIPTION
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.LP
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This utility shall only expand command \fIargument\fPs. It is used
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when a command is needed, as in the \fBthen\fP condition of
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an \fBif\fP command, but nothing is to be done by the command.
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.SH OPTIONS
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.LP
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None.
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.SH OPERANDS
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.LP
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See the DESCRIPTION.
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.SH STDIN
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.LP
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Not used.
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.SH INPUT FILES
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.LP
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None.
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.SH ENVIRONMENT VARIABLES
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.LP
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None.
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.SH ASYNCHRONOUS EVENTS
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.LP
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Default.
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.SH STDOUT
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.LP
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Not used.
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.SH STDERR
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.LP
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The standard error shall be used only for diagnostic messages.
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.SH OUTPUT FILES
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.LP
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None.
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.SH EXTENDED DESCRIPTION
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.LP
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None.
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.SH EXIT STATUS
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.LP
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Zero.
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.SH CONSEQUENCES OF ERRORS
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.LP
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Default.
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.LP
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\fIThe following sections are informative.\fP
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.SH APPLICATION USAGE
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.LP
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None.
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.SH EXAMPLES
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.sp
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.RS
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.nf
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\fB: ${X=abc}
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if false
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then :
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else echo $X
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fi
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\fP\fBabc\fP
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.fi
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.RE
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.LP
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As with any of the special built-ins, the null utility can also have
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variable assignments and redirections associated with it,
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such as:
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.sp
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.RS
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.nf
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\fBx=y : > z
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\fP
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.fi
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.RE
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.LP
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which sets variable \fIx\fP to the value \fIy\fP (so that it persists
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after the null utility completes) and creates or
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truncates file \fBz\fP.
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.SH RATIONALE
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.LP
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None.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fISpecial Built-In Utilities\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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