exec - abandon this program to run another
exec LIST
The 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 the section on ’STRING’ in the perlop manpage for details.