Shell script to check if a string contains something

Question

I have the following shell script.

  if [ "$group" == "First*" ]]
  then
            [email protected]
  elif [ "$group"  == "Second*" ]]
  then
           [email protected]
  fi

It does not throw any error , but does not execute the if statement properly if $group contains a First or a Second inside. Can any one tell me where I am going wrong.

Have you tried `if [ "$group" = "First*" ]]` I think in shell programming one equals sign is enough. — Jens, Aug 03 '14 at 07:05
firstly there is a syntax error you need to use either [ ] or [[ ]] secondly if the brackets are just typo then I think you want to use the wildcard * .. but when double quotes are used the wildcard looses it meaning — Ajay, Aug 03 '14 at 07:30
possible duplicate of [How do you tell if a string contains another string in Unix shell scripting?](http://stackoverflow.com/questions/2829613/how-do-you-tell-if-a-string-contains-another-string-in-unix-shell-scripting) — user123444555621, Aug 03 '14 at 10:47

Rahul Tripathi · Answer 1 · 2014-08-03T07:36:21.503

1

Remove the quotes "" and it is done

if [ "$group" == First* ]
then
        [email protected]
 elif [ "$group"  == Second* ]
 then
       [email protected]
 fi

edited Aug 03 '14 at 07:36

answered Aug 03 '14 at 07:05

Rahul Tripathi

168,305
31
280
331

score 1 · Answer 2 · answered Aug 03 '14 at 07:33

1

You can also consider a case statement for efficiency:

case "$group" in
First*)
    [email protected]
    ;;
Second*)
    [email protected]
    ;;
esac

You can add *) ... ;; as well for default action.

answered Aug 03 '14 at 07:33

konsolebox

72,135
12
99
105

why is this efficient? – user2890683 Aug 03 '14 at 07:37
1

@user2890683 `case` statements have less runtime overhead than other tests including `[[ ]]`. You also don't call a builtin twice for the test. And case statements are not even in the level of builtins. – konsolebox Aug 03 '14 at 07:39

score 0 · Answer 3 · answered Aug 03 '14 at 07:22

When we use double quotes the wildcard character are not retained ... the check condition is looking for a exact "First*" and "Second*" match .

change your code in following way

if [[ "$group" == First* ]]
   then
        [email protected]
   elif [[ "$group"  == Second* ]]
   then
       [email protected]
   fi

Shell script to check if a string contains something

3 Answers3