Run a program and capture its output

Question

I have a Perl script that runs a python script but i need to pass information back to the Perl script. Anyone can help me to achieve this?

This is my code so far

open(my $py, "|-", "python2 /home/pi/myRead.py") or die "Cannot run Python script: $!";
while (<$py>) {
    $newCard = $py;
}
close($py);

You keep overwriting $newCard instead of appending to it

ikegami
– ikegami

2017-08-30 18:34:53 +00:00
Commented Aug 30, 2017 at 18:34 — ikegami
– ikegami, Commented Aug 30, 2017 at 18:34
stackoverflow.com/questions/10765311/…

mpapec
– mpapec

2017-08-30 18:35:28 +00:00
Commented Aug 30, 2017 at 18:35 — mpapec
– mpapec, Commented Aug 30, 2017 at 18:35
"-|" is for reading.

mpapec
– mpapec

2017-08-30 18:37:25 +00:00
Commented Aug 30, 2017 at 18:37 — mpapec
– mpapec, Commented Aug 30, 2017 at 18:37

ikegami · Accepted Answer · 2017-08-30 18:34:34Z

3

my $newCard = `python2 /home/pi/myRead.py`;

answered Aug 30, 2017 at 18:34

ikegami

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7 Comments

Tiago Martins Over a year ago

I swear this was my first try and didn't work. worked now. TY

William Pursell Over a year ago

Don't use backticks. Use qx. eg. my $newCard = qx@ python /home/pi/myRead.py@;

ikegami Over a year ago

@William Pursell, Why??? `...` is short for qx`...`, which is short for readpipe(qq`...`).

ikegami Over a year ago

@William Pursell, You could argue that qx(...) is more readable, but that's not what you recommended.

ikegami Over a year ago

Argue on what basis? qq@@ adds noise, unfamiliarity and complexity, all deterrents to readability. On top of that, it changes the meaning of @, a huge reduction in readability. Finally, qq@@ also reduces usability (by preventing the interpolation of arrays). All that, and no benefits are added. It clearly hurts readability (and usability). /// On the other hand, qq() also adds noise and unfamiliarity, but also adds balanced delimiters which adds a modicum of readability. Enough to overcome the noise and unfamiliarity? debatable.

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