Visual Code Bash Snippets

Bash snippets for Visual Code

List of snippets

Redirect stdout to /dev/null

Prefix: 1
Render: >/dev/null

Redirect stderr to /dev/null

Prefix: 2
Render: 2>/dev/null

Redirect stdout & stderr to /dev/null

Prefix: 12 Render:>/dev/null 2>&1

Redirect to stderr

Prefix: e2 Render: >&2

cat until EOF

Prefix: cat
Render:

cat <<-EOF >/path/to/file

EOF

Notes

• The - option to mark a here document limit string (<<-EOF) suppresses leading tabs (but not spaces) in the output. This may be useful in making a script more readable.

• cat something to stdout by removing the redirection to file (>/path/to/file).

More about heredocuments

See http://tldp.org/LDP/abs/html/here-docs.html

Short 'if..then..else' (almost ternary operator)

Prefix: ite
Render: [[ condition ]] && echo "true" || echo "false" >&2

Notes

• Be sure the first command (echo "true") always exits with 0 otherwise, the second command will also be executed!

Example:

$ [[ 1 -eq 1 ]] && { echo "it's true"; false; } || echo "but it's also false" >&2
it's true
but it's also false

Read file line by line

Prefix: while read file
Render:

while read -r line
do
  ${2:echo "\$line"}
done < ${1:/path/to/file}

Parsing short command line arguments/parameters

Prefix: getopts
Render:

while getopts :?h arg
do
  case $arg in
    )
      : #statements
      ;;
    :|?|h)
      [[ $arg == \? ]] && print_error "L'arg -$OPTARG n'est pas prise en charge !"
      [[ $arg == : ]] && print_error "L'arg -$OPTARG requiert un argument !"
      usage
      exit $([[ $arg == h ]] && echo 0 || echo 2)
      ;;
  esac
done

Notes

• After triggering this snippet, you must enter a letter (or number) for the first argument, otherwise, script doesn't works.
• print_error is a custom function according to my needs to print message in red to stderr. You can replace it with echo "the error message" >&2.

Parsing short command line options/parameters

Same as above but with support of long options.

Prefix: getopts long
Render:

while getopts :?a-:fqvh arg
do
  case $arg in
    -)
      if [[ ${!OPTIND} == -* ]]
      then
        value=
      else
        value="${!OPTIND}"
        ((OPTIND++))
      fi
      case $OPTARG in
        host)
          HOST=$value
          ;;
        port)
          if [[ ! $value =~ ^[0-9]+$ ]]
          then
            print_error "L'arg --$OPTARG a besoin d'un entier en parametre. "$value" n'est pas un entier."
            usage
            exit 2
          fi
          ;;
        *)
          print_error "Le parametre '--$OPTARG' n'est pas reconnu !"
                usage
            exit 2
                ;;
        esac
      ;;
    a)
      [[ $OPTARG == -* ]] && print_error "L'option -$arg requiert un argument !" && usage && exit 2
      ;;
    )
      : #statements
      ;;
    f)
      FORCE=1
      ;;
    q)
      QUIET=1
      ;;
    v)
      VERBOSE=1
      ;;
    :|?|h)
      [[ $arg == \? ]] && print_error "L'option -$OPTARG n'est pas prise en charge !"
      [[ $arg == : ]] && print_error "L'option -$OPTARG requiert un argument !"
      usage
      exit $([[ $arg == h ]] && echo 0 || echo 2)
      ;;
  esac
done

More about getopts

See http://tldp.org/LDP/abs/html/internal.html#EX33

function template

Prefix: function! Render:

# TODO 's description
# @param  The first parameter
# @return
#
function_name() {
  local param_name="$1"; shift
  echo "TODO !"
}

usage function template

Prefix: usage Render:

usage() {
  cat <<-EOF
  Usage: pgihadmin tache <CIBLE> [-f] [-q] [-h]
  Cette tache permet de bla bla
  PARAMETRES:
  ===========
      CIBLE    Serveur cible : <vide> ou all, aps, ts, lb, ord, apsN, tsN, lbN, ordN (avec N un nombre)
  OPTIONS:
  ========
      -f    Mode force
      -q    Mode silencieux
      -h    Affiche ce message
  EOF
}

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