Re^3: Continuous or timed?

Thank you for all the information :)

Also, my general advice for running anything from cron is always use absolute paths

Following this advice I have used the full path so my cron entry is:

*/2 * * * * /usr/bin/perl /home/pi/Curtains/curtains.pl
[download]

If I use /usr/bin/perl /home/pi/Curtains/curtains.pl from the command line then the script runs but it doesn't run from cron. So I have enabled logging in /etc/rsyslog.conf and I get this logged:

Dec 14 16:12:01 eric CRON[10129]: (pi) CMD (/usr/bin/perl /home/pi/Cur
+tains/curtains.pl)
Dec 14 16:12:01 eric CRON[10128]: (CRON) info (No MTA installed, disca
+rding output)
Dec 14 16:14:01 eric CRON[10135]: (pi) CMD (/usr/bin/perl /home/pi/Cur
+tains/curtains.pl)
Dec 14 16:14:01 eric CRON[10134]: (CRON) info (No MTA installed, disca
+rding output)
[download]

That explains why I am not getting any mail! But doesn't explain to me why the script is not running from cron. I have tried chmod 777 curtains.pl and chmod 755 curtains.pl.

What else should I be looking at to try and debug this problem>

Comment on Re^3: Continuous or timed? Select or Download Code

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Re^4: Continuous or timed? by afoken (Chancellor) on Dec 14, 2020 at 19:46 UTC
`Dec 14 16:12:01 eric CRON[10128]: (CRON) info (No MTA installed, discarding output)` No Mail Transport Agent installed. Guess why you did not get any mail. You need to install and configure something like nullmailer, exim, postfix, or - if you like the pain - sendmail. Alternatively, redirect output of all cron jobs to log files or pipe through logger(1). Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply] [d/l]
Re^4: Continuous or timed? by haukex (Archbishop) on Dec 14, 2020 at 16:33 UTC
What else should I be looking at to try and debug this problem Well, `cron` runs its entries with a very limited environment. So for example, if you've set a custom `PERL5LIB` environment variable, such as by using local::lib to install modules into your home directory, then those settings that `perl` gets via the environment won't be present. If that's the problem here, there are a couple of possible solutions: you could set `PERL5LIB` explicitly in the `crontab`, you could `use lib`, write a wrapper script, or, IIRC I once did this with an file in `/etc/default`, but that might be overkill on a simple "single-user" RPi.	[reply] [d/l] [select]
Re^4: Continuous or timed? by stevieb (Canon) on Dec 14, 2020 at 16:33 UTC
What are the characteristics that you're using to identify that it runs at the CLI but not from cron?	[reply]
Re^5: Continuous or timed? by Bod (Parson) on Dec 14, 2020 at 16:47 UTC
What are the characteristics that you're using to identify that it runs at the CLI but not from cron? It writes a timestamped line to a logfile very close to the beginning of the script. The logfile uses an absolute path. `#!/usr/bin/perl use lib '.'; use Curtains::Control; use Bod::Config; use strict; my $DEBUG = 1; my $control = Curtains::Control->new; $control->log("Starting Curtain Controller") if $DEBUG;` [download] Could the location of the modules be an issue here as I've added `use lib '.';`?	[reply] [d/l] [select]
Re^6: Continuous or timed? by haukex (Archbishop) on Dec 14, 2020 at 16:50 UTC
Could the location of the modules be an issue here as I've added `use lib '.';`? Yes, definitely, don't rely on the CWD either when running from `cron`, use an absolute path. Also, BTW, you can see what Perl is outputting by appending e.g. `2>/tmp/stderr` to the `crontab` entry.	[reply] [d/l] [select]
Re^7: Continuous or timed? by stevieb (Canon) on Dec 14, 2020 at 16:59 UTC
Re^8: Continuous or timed? by Bod (Parson) on Dec 14, 2020 at 17:30 UTC
Re^7: Continuous or timed? by Bod (Parson) on Dec 14, 2020 at 17:13 UTC
Re^8: Continuous or timed? by stevieb (Canon) on Dec 14, 2020 at 17:19 UTC


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