Perl open not running shell commands

Question

Why does the following perl script not print anything?

if (open(my $fh, "| (while read LINE; do echo \$LINE; done )")) {
    print $fh "test";
    close($fh);
}

In sh, if I run echo 'test' | (while read LINE; do echo \$LINE; done ) I would expect to have test be printed out.

Side note, open my $fh, "|-", ".." as perl favors three args open. ("-|" to rad from pipe) — mpapec
– mpapec, Commented Aug 31, 2014 at 17:49

Mark Setchell · Accepted Answer · 2014-09-01 06:09:23Z

1

Add "\n" to your print, since read is looking for a whole line, like this

print $fh "test\n";

answered Aug 31, 2014 at 17:39

Mark Setchell

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3 Comments

It is best to $fh->autoflush so that you can print what you want

@Borodin, The thing is, test+newline is what he wants to print. $fh->autoflush won't help at all here.

@ikegami I have removed the erroneous part of the explanation - thank you for pointing it out.