Rafael M. rafaelmaeuer

## quote-shell-var.md

      
              1 file
            
          
              0 forks
            
          
              0 comments
            
          
              0 stars
            
          
                rafaelmaeuer
                / quote-shell-var.md
            
            
              Created
              August 28, 2023 09:19
            
              
                https://stackoverflow.com/questions/10067266/when-to-wrap-quotes-around-a-shell-variable/10067297#10067297
              
          
    General rule: quote it if it can either be empty or contain spaces (or any whitespace really) or special characters (wildcards). Not quoting strings with spaces often leads to the shell breaking apart a single argument into many.
$? doesn't need quotes since it's a numeric value. Whether $URL needs it depends on what you allow in there and whether you still want an argument if it's empty.
I tend to always quote strings just out of habit since it's safer that way.

  
## docker-compose-m1.sh
if [[ $(arch) == 'arm64' ]]; then
    export DOCKER_DEFAULT_PLATFORM=linux/amd64
fi

## apple-script-admin.scpt
do shell script "command" user name "username" password "pass" with administrator privileges

## gen-ssh-key.sh
ssh-keygen -o -a 100 -t ed25519 -C "Name-of-Machine"

## bash-argument-exists.sh
# variable $# is the number of input arguments
if [ $# -eq 0 ]
  then
    echo "No arguments supplied"
fi

# check if an argument is an empty string or not
if [ -z "$1" ]
  then
    echo "No argument supplied"

## check-var-empty.sh
# -n operator: check if var is not empty
VAR="test"
if [ -n "$VAR" ]; then
  echo "$VAR is not empty"
fi

# -z operator: check if var is empty
VAR=""
if [ -z "$VAR" ]; then
 echo "$VAR is empty"

## count-remove-oldest.sh
# The script receives the limit as an argument.
limit=$1

number_of_files=$(ls ./files | wc -l)

if [ $number_of_files -gt $limit ]
then
    # There are more files than the limit
    # So we need to remove the older ones.
    cd files

## shell-script-args.sh
wrappedProgram "$@"
# ^^^ this is correct and will hand over all arguments in the way
#     we received them, i. e. as several arguments, each of them
#     containing all the spaces and other uglinesses they have.
wrappedProgram "$*"
# ^^^ this will hand over exactly one argument, containing all
#     original arguments, separated by single spaces.
wrappedProgram $*
# ^^^ this will join all arguments by single spaces as well and
#     will then split the string as the shell does on the command

## loop-script-args.sh
for var in "$@"; do
  echo "$var"
done

## run-as-other-user.sh
su -c '/home/annie/annie-script.sh' annie
	if [[ $(arch) == 'arm64' ]]; then
	export DOCKER_DEFAULT_PLATFORM=linux/amd64
	fi
	# variable $# is the number of input arguments
	if [ $# -eq 0 ]
	then
	echo "No arguments supplied"
	fi

	# check if an argument is an empty string or not
	if [ -z "$1" ]
	then
	echo "No argument supplied"
	# -n operator: check if var is not empty
	VAR="test"
	if [ -n "$VAR" ]; then
	echo "$VAR is not empty"
	fi

	# -z operator: check if var is empty
	VAR=""
	if [ -z "$VAR" ]; then
	echo "$VAR is empty"
	wrappedProgram "$@"
	# ^^^ this is correct and will hand over all arguments in the way
	# we received them, i. e. as several arguments, each of them
	# containing all the spaces and other uglinesses they have.
	wrappedProgram "$*"
	# ^^^ this will hand over exactly one argument, containing all
	# original arguments, separated by single spaces.
	wrappedProgram $*
	# ^^^ this will join all arguments by single spaces as well and
	# will then split the string as the shell does on the command