bash: get only double dash or single dash options

userRG7b 0
Viewed 51

In a linux bash script, I want to have two lists of arguments: one are those started with single dash and the other those started with double dash. For example:

   script -a 1 --b=3 -c 7 --d=8

Then it can return them in two group variables:

  group1 : -a 1 -c 7
  group2 : --b=3 --d=8

I know that $@ holds a list of all arguments. I don't know whether I should iterate them and make them distinct or there are easier solutions. This is my try:

g1=""
g2=""
for i in $@; do
   echo $i
   if [[ $i == --* ]]; then
      g1="${g1} $i"
   else
      g2="${g2} $i"
   fi 
done
echo $g1
echo $g2

regardless of its accuracy, it says:

test.sh: 5: [[: not found
command-line-arguments bash linux
2 Answers

You may better use shell array to hold 2 different set of arguments. With few fixes this script should address it:

g1=()
g2=()

for i; do
   if [[ $i == '--'* ]]; then
      g1+=( "$i" )
   else
      g2+=( "$i" )
   fi 
done

echo "group1: ${g1[@]}"
echo "group2: ${g2[@]}"

Output:

group1: --b=3 --d=8
group2: -a 1 -c 7
anubhava0

Use a case/esac to facilitate the option parsing instead of a ìf. And use the shebang (#!) to choose the shell you want to use. I also added a case to manage parameters without options:

#!/bin/sh


g1=""
g2=""
for i in $@
do

   echo $i
   case $i in
       
       # -- option
       --*) g1="${g1} $i"; g=1;;
       
       # - option
       -*) g2="${g2} $i"; g=2;;
       
       # Parameter 
       *) p=$i
          if [ "$g" = 1 ]
          then
            g1="${g1} $p"
            g=0
          elif [ "$g" = 2 ]
          then
            g2="${g2} $p"
            g=0
          else
            others="$others $p"
          fi
      ;;
 
   esac

done
echo g1=$g1
echo g2=$g2
echo others=$others

Example of runs:

$ ./t.sh -o opt --t -h --h --p param param2
-o
opt
--t
-h
--h
--p
param
param2
g1= --t --h --p param
g2= -o opt -h
others= param2
$ ./t.sh file -o --t --p param
file
-o
--t
--p
param
g1= --t --p param
g2= -o
others= file
Rachid K.0
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