Is there a way to wrap the following linux command into the Perl system function?

date --set="$(ssh [email protected] 'date -u')"

I have tried the following but cannot find a combination that works:

use strict;
system("date --set="$(ssh [email protected] 'date -u')"");
system, "date", "--set="$(ssh [email protected] 'date -u')"";

CodePudding user response：

You can use backticks to run a command through your shell. The backtick is an experssion that evaluates to the standard output of the command you execute.

use strict;
my $remote_date = `ssh richard\@192.168.0.4 'date -u'`;
chomp $remote_date;
system("date --set='$remote_date'");

The variable $remote_date will contain whatever ssh would print on the screen, including, possibly, login messages. The newline programs typically print at the end of every line will also be included, so I threw in a chomp.

This assumes the command ran succesfully. You can check the exit status of a program with the $? variable, but I am not sure, in your case, if this would give you the status of ssh or the remote date command you attempted to execute.

CodePudding user response：

wrap commands in Perl, with or without variables/special characters:

use strict; use warnings;
my $remote_date = system<<'EOF';
ssh [email protected] 'date -u'
EOF
chomp $remote_date;
system<<EOF;
date --set='$remote_date'
EOF

Check perldoc perlop#Quote-and-Quote-like-Operators

Especially the part about 'QuoteHereDocument'

CodePudding user response：

The problem is that you didn't escape the ", $ and @ within.

system( "date --set=\"\$( ssh richard\@192.168.0.4 'date -u' )\"" );

In this case, it's cleaner to use single-quotes on the outside, and double-quotes on the inside.

system( 'date --set="$( ssh [email protected] "date -u" )"' );