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How can I check for apt-get errors in a bash script?

rated 0 times [ 15] [ 0] / answers: 1 / hits: 18154 / 2 Years ago, sun, december 26, 2021, 3:23:21

I am writing a bash script to install software and update Ubuntu 12.04. I would like the script to be able to check for apt-get errors especially during apt-get update so that I can include corrective commands or exit the script with a message. How can I have my bash script check for these types of errors?

Edit March 21st:
Thank you terdon for the providing just the information I needed! Here is the script I created with a combination of your suggestions to check for updates and recheck when errors occur and then report back. I will be adding this to a longer script that I am using to customize new Ubuntu installations.



#!/bin/bash



apt-get update



if [ $? != 0 ]; 

then

    echo "That update didn't work out so well. Trying some fancy stuff..."

    sleep 3

    rm -rf /var/lib/apt/lists/* -vf

    apt-get update -f || echo "The errors have overwhelmed us, bro." && exit

fi



echo "You are all updated now, bro!"

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1 Year ago

answered 2 Years ago enincroscope · Accepted Answer

The simplest approach is to have your script continue only if apt-get exits correctly. For example:

sudo apt-get install BadPackageName && 

## Rest of the script goes here, it will only run

## if the previous command was succesful

Alternatively, exit if any steps failed:

sudo apt-get install BadPackageName || echo "Installation failed" && exit

This would give the following output:

terdon@oregano ~ $ foo.sh

[sudo] password for terdon: 

Reading package lists... Done

Building dependency tree       

Reading state information... Done

E: Unable to locate package BadPackageName

Installation failed

This is taking advantage of a basic feature of bash and most (if not all) shells:

&& : continue only if the previous command succeeded (had an exit status of 0)

||: continue only if the previous command failed (had an exit status of not 0)

It is the equivalent of writing something like this:

#!/usr/bin/env bash



sudo apt-get install at



## The exit status of the last command run is 

## saved automatically in the special variable $?.

## Therefore, testing if its value is 0, is testing

## whether the last command ran correctly.

if [[ $? > 0 ]]

then

    echo "The command failed, exiting."

    exit

else

    echo "The command ran succesfuly, continuing with script."

fi

Note that if a package is already installed, apt-get will run successfully, and the exit status will be 0.