exec() function executes a system command AND NEVER RETURNS - use system() instead of exec() if you want it to return. It fails and returns
FALSE only if the command does not exist
and it is executed directly instead of via your system's command shell (see
below).
If there is more than one argument in
LIST, or if
LIST is an array with more than one value, calls execvp(3) with the arguments in
LIST. If there is only one scalar argument, the argument is checked for shell metacharacters, and if there are any, the entire argument is passed to the system's command shell for parsing (this is
/bin/sh -c on Unix platforms, but varies on other platforms). If there are no shell
metacharacters in the argument, it is split into words and passed directly
to execvp(), which is more efficient. Note:
exec() and system() do not flush your output
buffer, so you may need to set $|
to avoid lost output. Examples:
exec '/bin/echo', 'Your arguments are: ', @ARGV;
exec "sort $outfile | uniq";
If you don't really want to execute the first argument, but want to lie to the program you are executing about its own name, you can specify the program you actually want to run as an ``indirect object'' (without a comma) in front of the LIST. (This always forces interpretation of the LIST as a multivalued list, even if there is only a single scalar in the list.) Example:
$shell = '/bin/csh';
exec $shell '-sh'; # pretend it's a login shell
or, more directly,
exec {'/bin/csh'} '-sh'; # pretend it's a login shell
When the arguments get executed via the system shell, results will be subject to its quirks and capabilities. See `STRING` for details.