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Bash scripts

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ShellCheck

Bash boilerplates

set

set or unset values

#

# Do
set -o nounset
# Catch the error in case mysqldump fails (but gzip succeeds) in `mysqldump |gzip`
set -o pipefail
# Turn on traces, useful while debugging but commented out by default
# set -o xtrace
-e - Exit immediately if a command exits with a non-zero status

| | -o <option_name> | --option-name | | -o errexit | - exit on error

  • Append "|| true" if you expect an error | | -o errtrace | - Exit on error inside any functions or sub-shells | | -o nounset | - no undefined vars
  • Use ${VAR:-} to use an undefined var | | -u | reference a variable that hasn’t been previously defined? throw an error | | -x | all executed commands are printed to the terminal |
  • cmd1 | cmd2 | cmd3
  • if any of the commands fail, exit with an error

  • pipeline to return the exit status of the last (rightmost) command to exit with a non-zero status

See bash page for more bash goodies

Last update: 2023-04-24