Run program in perl script

It also significantly increases the difficulty of error handling. If you can turn your external program into a module, you may find it simplifies your overall design. You already got good answers to your question, but there's always the posibility to take a different point of view: maybe you should consider refactoring the script that you want to run from the first script. Turn the functionality into a module.

Use the module from the first and from the second script. I can think of a few ways to do this. You already mentioned the first two, so I won't go into detail on them. The eval can be accomplished by slurping the other file into a string or a list of strings , then 'eval'ing the strings.

Heres a sample:. If you need to asynchronously call your external script -you just want to launch it and not wait for it to finish-, then :. See the perlipc documentation for several options for interprocess communication. If your first script merely sets up the environment for the second script, you may be looking for exec. This will start the process date and pipe the output of the command to the OUTPUT filehandle which you can process a line at a time.

When the command is finished you can close the output filehandle and retrieve the return value of the process. Replace date with whatever you want. I wanted to do something like this to offload non-subroutines into an external file to make editing easier. I actually made this into a subroutine. The advantage of this way is that those "my" variables in the external file get declared in the main namespace.

If you use 'do' they apparently don't migrate to the main namespace. Note the presentation below doesn't include error handling. How are we doing? Please help us improve Stack Overflow. Take our short survey. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams?

Collectives on Stack Overflow. Learn more. How do I run a Perl script from within a Perl script? It has two separate effects. For instance, to trim lines to 80 columns:. This loads the module, but does not call its import method, so does not import subroutines and does not give effect to a pragma. This loads the module and calls its import method, causing the module to have its default effect, typically importing subroutines or giving effect to a pragma. You can use quotes to add extra code after the module name, e.

If the first character after the -M or -m is a dash - then the 'use' is replaced with 'no'. This makes no difference for -m. This avoids the need to use quotes when importing symbols. Note that the lines are not printed by default. See "-p" to have lines printed.

If a file named by an argument cannot be opened for some reason, Perl warns you about it and moves on to the next file. See perlop for possible security implications. This is faster than using the -exec switch of find because you don't have to start a process on every filename found but it's not faster than using the -delete switch available in newer versions of find. It does suffer from the bug of mishandling newlines in pathnames, which you can fix if you follow the example under If a file named by an argument cannot be opened for some reason, Perl warns you about it, and moves on to the next file.

Note that the lines are printed automatically. An error occurring during printing is treated as fatal. To suppress printing use the "-n" switch. A -p overrides a -n switch. Also, when using this option on a script with warnings enabled you may get a lot of spurious "used only once" warnings. On some platforms, this also makes Perl append suffixes to the filename while searching for it. For example, on Win32 platforms, the ". Typically this is used to emulate! It's also convenient when debugging a script that uses!

The shell executes the second line as a normal shell command, and thus starts up the Perl interpreter. After Perl locates the program, it parses the lines and ignores them because the check 'if 0' is never true.

To start up sh rather than csh , some systems may have to replace the! Other systems can't control that, and need a totally devious construct that will work under any of csh , sh , or Perl, such as the following:. If the filename supplied contains directory separators and so is an absolute or relative pathname , and if that file is not found, platforms that append file extensions will do so and try to look for the file with those extensions added, one by one.

On DOS-like platforms, if the program does not contain directory separators, it will first be searched for in the current directory before being searched for on the PATH.

Like "-T" , but taint checks will issue warnings rather than fatal errors. These warnings can now be controlled normally with no warnings qw taint. Note: This is not a substitute for -T! This is meant to be used only as a temporary development aid while securing legacy code: for real production code and for new secure code written from scratch, always use the real "-T". Ordinarily these checks are done only when running setuid or setgid.

It's a good idea to turn them on explicitly for programs that run on behalf of someone else whom you might not necessarily trust, such as CGI programs or any internet servers you might write in Perl. See perlsec for details. For security reasons, this option must be seen by Perl quite early; usually this means it must appear early on the command line or in the!

This switch causes Perl to dump core after compiling your program. You can then in theory take this core dump and turn it into an executable file by using the undump program not supplied. This speeds startup at the expense of some disk space which you can minimize by stripping the executable. Still, a "hello world" executable comes out to about K on my machine. If you want to execute a portion of your program before dumping, use the CORE::dump function instead.

Note: availability of undump is platform specific and may not be available for a specific port of Perl. Currently the only "unsafe" operations are attempting to unlink directories while running as superuser and running setuid programs with fatal taint checks turned into warnings.

Note that warnings must be enabled along with this option to actually generate the taint-check warnings. Prints to STDOUT the value of the named configuration variable s , with multiples when your configvar argument looks like a regex has non-letters. For example:. Additionally, extra colons can be used to control formatting. A trailing colon suppresses the linefeed and terminator ";", allowing you to embed queries into shell commands.

Leading and trailing colons can be used together if you need positional parameter values without the names. See also perldiag and perltrap. A fine-grained warning facility is also available if you want to manipulate entire classes of warnings; see warnings.

See warnings. Leading garbage will be discarded until the first line that starts with! Any meaningful switches on that line will be applied. All references to line numbers by the program warnings, errors, Thus a warning on the 2nd line of the program, which is on the th line in the file will be reported as line 2, not as line This can be overridden by using the line directive. See "Plain Old Comments Not!

If a directory name is specified, Perl will switch to that directory before running the program. The -x switch controls only the disposal of leading garbage. The directory, if specified, must appear immediately following the -x with no intervening whitespace. Used in executing subprocesses, and in finding the program if "-S" is used. A list of directories in which to look for Perl library files before looking in the standard library.

These typically would be for older compatible perl versions installed in the same directory tree. The program should instead say:. Command-line options switches. Switches in this variable are treated as if they were on every Perl command line. When running taint checks either because the program was running setuid or setgid, or because the "-T" or "-t" switch was used , this variable is ignored. A space or colon separated list of PerlIO layers.

It is conventional to start layer names with a colon for example, :perlio to emphasize their similarity to variable "attributes". But the code that parses layer specification strings, which is also used to decode the PERLIO environment variable, treats the colon as a separator. The list becomes the default for all Perl's IO.

Consequently only built-in layers can appear in this list, as external layers such as :encoding need IO in order to load them! See "open pragma" for how to add external encodings as defaults.

For more details see PerlIO. This is a re-implementation of stdio-like buffering written as a PerlIO layer. As such it will call whatever layer is below it for its operations, typically :unix. The layer provides both buffering and IO. Note that the :stdio layer does not do CRLF translation even if that is the platform's normal behaviour. You will need a :crlf layer above it to do that. Name Spaces and Perl Module Files. Symbolic or Soft References. Hard References - Addresses of Memory Objects.

Objects or References and Classes or Packages. Typeglob and Importing Identifiers from Other Packages. String Built-in Functions and Performance. Open Files in Binary Mode. Open Directories and Read File Names. File System Functions and Operations. Image and Picture Processing. Socket Communication Over the Internet.

XML Communication Model. Integrating Perl with Apache Web Server. Converting Perl Script to Executable Binary. Archived Tutorials.