I would like to call an application from a perl script using the 'system' command. However, the application is placed in a separate directory. How can I call the application from that directory in my perl script. Can I use "require"?
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2 Answers
You can just change directory if you want to run the application in the directory where the application resides. See the chdir command in perlfunc.
Otherwise, just add the path like this:
system('/path/to/the/application');
Comments
No, require doesn't work -- require is used to pull in other perl files, once. If, of course, the file you'd like to call to is a perl program ... well, it's probably better to factor out the parts you'd like to be shared between the two programs, rather than requireing it, or to simply treat it as a black box anyway if you don't want to do that.
To call an executable which is neither in the search path -- simply being in the same directory is not sufficient! -- supply the full path to, e.g. system, exec, &c.. For system, the preferred forms would be:
system { '/path/to/executable' } 'argument 0 (i.e. $0) supplied to program', 'argument 1 (equivalent to $ARGV[0])', ...;
or
# $path = ...
system $path 'arg 0', 'arg 1', ...;
or
# $path = ...
system $path @args;
Of course, it is good form to check the result of each system call in case of errors.
Note the use of indirect-object (i.e. with an argument passed without comma, like the fh for a print or such) system in every case! Unless you know very well what you're doing and why, it's hard to recommend risk using the one-argument form of system, because it subjects your input to the whims of shell preprocessing.
Consult perldoc -fsystem and perldoc -fexec for more detail.
