Bash script produces empty file

Question

I have created a script so I can search for 0kb files in a certain path, the output is to be redirected to a text file and then emailed. The script works except that the fie is empty either when it's emailed or when it's viewed after the script runs.

if [[ -n $(find /path/to/files/ -type f -empty -mmin +2) ]] then
> /tmp/output.txt ; mail -s "subject" -a /tmp/output.txt "email@address"
rm /tmp/ftr_output.txt
fi

Not sure if I missed something so any help would be appreciated.

Thanks

You have explicitly instructed that /tmp/output.txt be truncated. Why do you expect content to be in there? What are you trying to achieve? — devnull
– devnull, Commented May 8, 2014 at 2:40
I'm guessing > /tmp/output.txt was supposed to be inside the $() — technosaurus
– technosaurus, Commented May 8, 2014 at 8:33

hek2mgl · Accepted Answer · 2014-05-08 07:09:14Z

3

I guess you want something like this:

# Save find results in a text file
find /path/to/files/ -type f -empty -mmin +2 > /tmp/output.txt

# Check that the text file isn't empty (meaning no results from find)
if [ -s /tmp/output.txt ]
then
    # Send the text file along with an email
    mail -s "subject" -a /tmp/output.txt "email@address"
fi
# Remove the text file
rm /tmp/output.txt

edited May 8, 2014 at 7:09

answered May 8, 2014 at 2:51

hek2mgl

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10 Comments

William Pursell Over a year ago

The test will always fail. Try ` find ... > /tmp/output.txt; if [[ -n /tmp/output.txt ]] ...`

that other guy Over a year ago

@WilliamPursell That test will always pass :) Use -s

that other guy Over a year ago

I suggest this awesome hack: if find .. | grep "" > file

that other guy Over a year ago

wc -l file outputs 0 file, not just 0. For this approach, you could go with [[ -s, which checks for non-empty file and avoids counting lines at all.

Jonathan Leffler Over a year ago

You need the rm /tmp/output.txt after the fi so that it is removed even when it is empty. Arguably, the name should be decorated with $$ or created with the mktemp command.

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