Sample Script

Home › DevOps › Programming Languages › Scripting › Bash

Description

A bash script is a series of commands written in a file. These are read and executed by the bash command-line interpreter program. The program executes line by line. For example, you can navigate to a certain path, create a folder and spawn a process inside it using the command line.^[1]

example

#!/usr/bin/env bash

set -o errexit
set -o errtrace
set -o nounset
set -o pipefail

setting options

set -o <option> is the generic way to set various options.

errexit

set -e is a shortcut for setting the errexit option.
- set -o errexit has the same effect.
- The set -e option instructs bash to immediately exit if any command has a non-zero exit status; subsequent lines of the script are not executed.^[2]
- By default, bash does not do this… if it encounters a runtime error, it does not halt execution of the program; it keeps going and if one line in a script fails, but the last line succeeds, the whole script has a successful exit code.^[2:1]

errtrace

set -E is a shortcut for setting the errtrace option.
- set -o errtrace has the same effect.
- When errtrace is enabled, the ERR trap is also triggered when the error (a command returning a nonzero code) occurs inside a function or a subshell. Another way to put it is that the context of a function or a subshell does not inherit the ERR trap unless errtrace is enabled.^[3]