Bash "inline" conventions

Question

My goal is to add an argument to the executable if there is a bash variable like this:

bob -a some_arg (( if we have ${VAR} defined add '-b ${VAR}' as an argument ))

I would like to avoid something like:

if [[ -z ${VAR} ]]; then
    bob -a some_arg
else
    bob -a some_arg -b ${VAR}
fi

Although this is the only option?

+5

Matoe 30 sept '12 at 15:02

2 answers

You can use an array for this (see Arrays ):

args=( -a some_args )
if [ ... ] ; then
  args+=( -b "${VAR}" )
fi
bob "${args[@]}"

+2

Mat 30 sept '12 at 15:06

Gilles quenot · Accepted Answer · 2012-09-30T15:16:21+0000

Using the bash extension:

bob -a some_arg ${VAR:+-b "$VAR"}

And LANG=C man bash | less +/'Parameter Expansion'