Sample Script

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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

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#!/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]

  1. https://www.freecodecamp.org/news/shell-scripting-crash-course-how-to-write-bash-scripts-in-linux ↩︎

  2. https://gist.github.com/mohanpedala/1e2ff5661761d3abd0385e8223e16425 ↩︎ ↩︎

  3. https://stackoverflow.com/a/25380229 ↩︎