‘ls’ terminated by signal 13 when using find command [duplicate]

Question

so I'm attempting to run a script which searches the contents of df -h for a directory that exceeds threshold, and basically run a find command on that directory to get the top ten largest files, then stop running find. However, when it gives the top ten files, as intended, it then spits out several times:

find: ‘ls’ terminated by signal 13

My question is simply, how do I stop these? I think I understand that these are due to my find command and head -n 10 command running at the same time, as head is piped after find, but if someone could elaborate, that would be great. My goal is to submit this to the powers that be at work (Walmart) to have this start being ran on our test servers.

Also note below, that the size in the find command is only 5M, as my test server does not have 10 files on it that are that big in that directory.

Here is the script:

#!/bin/bash

#defines what exceeds threshold

threshold="90%|91%|92%|93%|94%|95%|96%|97%|98%|99%|100%|6%"

#puts the output of df -h  into output_df

df -h > output_df

cat output_df | awk -v VAR=$threshold '{if($5~VAR)print $6}' > exceeds_thresh

LINES=()
while IFS= read -r exceeds_thresh
do
find $exceeds_thresh -xdev -size +5M -exec ls -lah {} \; | head -n 10
done < "exceeds_thresh"

#cleaning up the files the script created

rm output_df exceeds_thresh

and here is a sample output:

-rw-r-----+ 1 root systemd-journal 16M Jun  1 19:18 /var/log/journal/a237b5bc574941af85c796e15b0ce420/system.journal
-rw-r-----+ 1 root systemd-journal 8.0M May 29 05:38 /var/log/journal/a237b5bc574941af85c796e15b0ce420/[email protected]~
-rw-r-----+ 1 root systemd-journal 104M Jun  1 05:55 /var/log/journal/a237b5bc574941af85c796e15b0ce420/system@45697f9ed4b84f07b92c5fcbc8a945bd-0000000000000001-00056d51a40f2f0c.journal
find: ‘ls’ terminated by signal 13
find: ‘ls’ terminated by signal 13
find: ‘ls’ terminated by signal 13
find: ‘ls’ terminated by signal 13
find: ‘ls’ terminated by signal 13
find: ‘ls’ terminated by signal 13
find: ‘ls’ terminated by signal 13
find: ‘ls’ terminated by signal 13

Answer 1

It is nothing to worry about. It is a broken pipe because head will finish reading the first 10 lines before all of the lines are written to stdout.

You can silence it with >/dev/null 2>&1 on the end or 2>/dev/null to just silence the errors. I've also seen another trick where you add tail -n +1 into the pipeline:

find $exceeds_thresh -xdev -size +5M -exec ls -lah {} \; | tail -n +1 | head -n 10

This is going to cost you some time, but it will work without changing the outcome.

Answer 2

The message is harmless, but annoying. It happens because head exits when it's gotten its fill of input lines, yet find keeps running and executing more ls calls. Those ls commands try to print and end up being killed with a SIGPIPE because there's nobody listening to them any longer.

You could use 2>/dev/null to hide the errors, but that'd also hide other legitimate errors. A more surgical approach would be:

find ... \; 2> >(grep -v 'terminated by signal 13' >&2) | head -n 10

This uses process substitution to filter out only the one message. 2> redirects stderr into the grep and >&2 redirects any surviving messages back to stderr.

This isn't perfect as find doesn't know that it should quit. It keeps running doomed lses long after head has exited.