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eval(1posix) [posix man page]

EVAL(P) 						     POSIX Programmer's Manual							   EVAL(P)

NAME
eval - construct command by concatenating arguments SYNOPSIS
eval [argument ...] DESCRIPTION
The eval utility shall construct a command by concatenating arguments together, separating each with a <space>. The constructed command shall be read and executed by the shell. OPTIONS
None. OPERANDS
See the DESCRIPTION. STDIN
Not used. INPUT FILES
None. ENVIRONMENT VARIABLES
None. ASYNCHRONOUS EVENTS
Default. STDOUT
Not used. STDERR
The standard error shall be used only for diagnostic messages. OUTPUT FILES
None. EXTENDED DESCRIPTION
None. EXIT STATUS
If there are no arguments, or only null arguments, eval shall return a zero exit status; otherwise, it shall return the exit status of the command defined by the string of concatenated arguments separated by <space>s. CONSEQUENCES OF ERRORS
Default. The following sections are informative. APPLICATION USAGE
None. EXAMPLES
foo=10 x=foo y='$'$x echo $y $fooeval y='$'$x echo $y 10 RATIONALE
None. FUTURE DIRECTIONS
None. SEE ALSO
Special Built-In Utilities COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol- ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html . IEEE
/The Open Group 2003 EVAL(P)

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COLON(P)						     POSIX Programmer's Manual							  COLON(P)

NAME
colon - null utility SYNOPSIS
: [argument ...] DESCRIPTION
This utility shall only expand command arguments. It is used when a command is needed, as in the then condition of an if command, but noth- ing is to be done by the command. OPTIONS
None. OPERANDS
See the DESCRIPTION. STDIN
Not used. INPUT FILES
None. ENVIRONMENT VARIABLES
None. ASYNCHRONOUS EVENTS
Default. STDOUT
Not used. STDERR
The standard error shall be used only for diagnostic messages. OUTPUT FILES
None. EXTENDED DESCRIPTION
None. EXIT STATUS
Zero. CONSEQUENCES OF ERRORS
Default. The following sections are informative. APPLICATION USAGE
None. EXAMPLES
: ${X=abc} if false then : else echo $X fi abc As with any of the special built-ins, the null utility can also have variable assignments and redirections associated with it, such as: x=y : > z which sets variable x to the value y (so that it persists after the null utility completes) and creates or truncates file z. RATIONALE
None. FUTURE DIRECTIONS
None. SEE ALSO
Special Built-In Utilities COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol- ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html . IEEE
/The Open Group 2003 COLON(P)

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