Aborting a shell script if any command returns a non-zero value

Add this to the beginning of the script:

set -e

This will cause the shell to exit immediately if a simple command exits with a nonzero exit value. A simple command is any command not part of an if, while, or until test, or part of an && or || list.

See the bash(1) man page on the "set" internal command for more details.

I personally start almost all shell scripts with "set -e". It's really annoying to have a script stubbornly continue when something fails in the middle and breaks assumptions for the rest of the script.

To add to the accepted answer:

Bear in mind that set -e sometimes is not enough, specially if you have pipes.

For example, suppose you have this script

#!/bin/bash
set -e 
./configure  > configure.log
make

... which works as expected: an error in configure aborts the execution.

Tomorrow you make a seemingly trivial change:

#!/bin/bash
set -e 
./configure  | tee configure.log
make

... and now it does not work. This is explained here, and a workaround (Bash only) is provided:

#!/bin/bash
set -e 
set -o pipefail

./configure  | tee configure.log
make

The if statements in your example are unnecessary. Just do it like this:

dosomething1 || exit 1

If you take Ville Laurikari's advice and use set -e then for some commands you may need to use this:

dosomething || true

The || true will make the command pipeline have a true return value even if the command fails so the the -e option will not kill the script.