Shell script error handling

Question

I'm cleaning the output of my scripts. For example:

rm -f ./file

No such file or directory

I want to implement some error checking for this command, equivalent to a try/catch statement. In other words, I want to catch the error if the command fails.

rm -f blahblahblah does not print an error message on my system. Does it on yours? What system? — John Zwinck
– John Zwinck, Commented Jan 8, 2015 at 4:43

l0b0 · Accepted Answer · 2015-01-08 08:38:44Z

4

Python:

try:
    os.remove('./file')
    champagne_for_everybody
except:
    throw_myself_in_the_river

Shell:

if rm ./file
then
    champagne_for_everybody
else
    throw_myself_in_the_river
fi

Notes:

Don't use -f - POSIX rm ignores missing files when using -f.
Don't use shell if you can avoid it. Python and other modern languages have much more sophisticated error handling built in.

answered Jan 8, 2015 at 8:38

l0b0

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Comments

buydadip · Accepted Answer · 2015-01-08 15:44:43Z

3

Why not use a simple script?

file=$1
if [ ! -f $file ]; then
    echo "File not found!"
else 
    rm -f $file
fi

When you run it, the script will tell you whether a given file does not exist.

You can also redirect to both stderr and stdout by using 2>&1 after the echo command. You may also add an exit 1 at the end of the if statement, because an exit status of 1 generally indicates that the command was not executed successfully.

This will not work in the exact way as you intend it to, but in bash this is the closest way of detecting errors.

edited Jan 8, 2015 at 15:44

answered Jan 8, 2015 at 5:05

buydadip

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Comments

midori · Accepted Answer · 2015-01-08 04:44:34Z

2

use set -e or you can achive same behaviour using && or ||

answered Jan 8, 2015 at 4:44

midori

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