This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding Linux
manual page for details of Linux behavior), or the interface may not be
implemented on Linux.
eval — construct command by concatenating arguments
utility shall construct a command by concatenating
s together, separating each with a <space> character. The
constructed command shall be read and executed by the shell.
See the DESCRIPTION.
The standard error shall be used only for diagnostic messages.
If there are no argument
s, or only null argument
shall return a zero exit status; otherwise, it shall return the exit status of
the command defined by the string of concatenated argument
by <space> characters, or a non-zero exit status if the concatenation
could not be parsed as a command and the shell is interactive (and therefore
did not abort).
The following sections are informative.
is not required to recognize the "--"
options delimiter, in cases where the argument(s) to eval
it is recommended that the first argument is prefixed by a
string that will not alter the commands to be executed, such as a
This standard allows, but does not require, eval
. Although this means applications cannot use
to protect against options supported as an extension (or
errors reported for unsupported options), the nature of the eval
utility is such that other means can be used to provide this protection (see
APPLICATION USAGE above).
, Special Built-In Utilities
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2013 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
7, Copyright (C) 2013 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. (This is POSIX.1-2008 with the 2013
Technical Corrigendum 1 applied.) 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.unix.org/online.html .
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