bash Script Arguments grouping

Question

I am having problems with expansion of command-line options containing spaces. They are not getting grouped as I expect them to be. How can I modify following code(below) to get the desired output(below).

function myFunction {
  while getopts "a:b:A:" optionName; do
    echo "$optionName::$OPTARG"
  done
}

#dynamic variable, cannot be hardcoded into $MY_ARGS
MY_VAR="X1=162356374 X2=432876 X3=342724"

#$MY_ARGS is useful and will be used more than once,
#so we don't want to eliminate it and replace it's usage with its value everywhere
MY_ARGS="-a 24765437643 -b '$MY_VAR' -A jeeywewueuye"

myFunction $MY_ARGS

Actual Output:

a::24765437643
b::'X1=162356374

Desired Output:

a::24765437643
b::X1=162356374 X2=432876 X3=342724
A::jeeywewueuye

John Kugelman · Accepted Answer · 2015-01-23 22:06:32Z

4

The best way to store a list of arguments is in an array. An array can handle arguments with whitespace without problem, and you don't have to figure out how to get the quotes and backslashes just right.

MY_ARGS=(-a 24765437643 -b "$MY_VAR" -A jeeywewueuye)

myFunction "${MY_ARGS[@]}"

The only unnatural part about arrays is the weird syntax to expand them: "${array[@]}". The quotes, curly braces, and [@] notation are all important.

edited Jan 23, 2015 at 22:06

answered Jan 23, 2015 at 22:00

John Kugelman

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1 Comment

glenn jackman Over a year ago

More than just the best way, it's the only way.

Walter A · Accepted Answer · 2015-01-24 14:50:56Z

I agree that arrays answer the question in the best way.
Perhaps you don't want to use arrays (colleagues will not understand), or you must obey the Google Guidelines for bash (nice work, I agree with for over 90%). that claims: "If you find you need to use arrays for anything more than assignment of ${PIPESTATUS}, you should use Python. ".
When you must look for another solutions:

An ugly solution is changing the IFS:

function myFunction {
  while getopts "a:b:A:" optionName; do
    echo "$optionName::$OPTARG"
  done
}

#dynamic variable, cannot be hardcoded into $MY_ARGS
MY_VAR="X1=162356374 X2=432876 X3=342724"

MY_ARGS="-a/24765437643/-b/"$MY_VAR"/-A/jeeywewueuye"

IFS=/
myFunction ${MY_ARGS}

Perhaps you want to do something with myFunction

function myFunction {
  while getopts "a:bA:" optionName; do
    case "${optionName}" in
       b) echo "${optionName}::${MY_VAR}" ;;
       *) echo "${optionName}::${OPTARG}" ;;
    esac
  done
}

or you could tr the spaces into another character before calling myFunction and tr the characters back to spaces in myFunction().

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