Question

i am trying to remotely execute a perl script that takes data from stdin, over ssh.
The tricky part is that i don’t want to upload the script itself to the remote server.
The data that the remote script will read from stdin is produced by another perl script run locally.

Let’s assume the following:

• my local script producing data is called cron_extract_section.pl
• my local script that will be run remotely is called cron_update_section.pl
• both scripts take one argument on the command line, a simple word

I manage to execute the script remotely, if the script is present on the remote machine:

./cron_extract_section.pl ${SECTION} 2> /dev/null | ssh user@remote ~/path/to/remote/script/cron_update_section.pl ${SECTION}

I know also that i can run a script on a remote server without having to upload it first, using the following syntax:

ssh user@remote "perl - ${SECTION}" < ./cron_update_section.pl

What i can’t figure out is how to feed the local script cron_update_section.pl over ssh to perl, AND also pipe the result of the local script cron_extract_section.pl to perl.

I tried the following, the perl script executes fine, but there is nothing to read from stdin:

./cron_extract_section.pl ${SECTION} 2> /dev/null | ssh user@remote perl - ${SECTION} < ./cron_update_section.pl

Do you know if it’s possible to do so without modifying the scripts ?

Answer 1

Use the DATA file handle. In example:

Local script to be run on the remote machine:

# script.pl
while(<DATA>) {
  print "# $_";
}
__DATA__

Then, run it as:

(cat script.pl && /cron_extract_section.pl ${SECTION}) | ssh $host perl