String comparison in bash not found

Question

I am trying to compare strings in bash  I already found an answer on how to do it on stackoverflow  In script I am trying  I am using the code submitted by Adam in the mentioned question      bin bash string  My string    if      string      My     then   echo  It s there    fi  needle  y s  if      string        needle       then   echo  haystack   string  contains needle   needle   fi   I also tried approach from ubuntuforums that you can find in 2nd post  if     var    regexp     then    do something fi   In both cases I receive error       not found   What am I doing wrong

User · Answer

Specify bash instead of sh when running the script  I personally noticed they are different under ubuntu 12 10   bash script sh arg0     argn

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If you know you re on bash  and still get this error  make sure you write the if with spaces    1  1     This outputs error     1  1      OK

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As  Ansgar mentioned     is a bashism  ie built into Bash and not available for other shells  If you want your script to be portable  use    Comparisons will also need a different syntax  change    to

User · Answer

How you are running your script  If you did with    sh myscript   you should try     bash myscript   or  if the script is executable       myscript   sh and bash are two different shells  While in the first case you are passing your script as an argument to the sh interpreter  in the second case you decide on the very first line which interpreter will be used

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is a bash-builtin  Your  bin bash doesn t seem to be an actual bash  From a comment  Add    bin bash at the top of file

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I had this problem when installing Heroku Toolbelt  This is how I solved the problem    ls -l  bin sh lrwxrwxrwx 1 root root 4 ago 15  2012  bin sh - gt  dash   As you can see   bin sh is a link to  dash   not bash   and    is bash syntactic sugarness  So I just replaced the link to  bin bash  Careful using rm like this in your system     sudo rm  bin sh   sudo ln -s  bin bash  bin sh

User · Answer

Is the first line in your script      bin bash   or     bin sh   the sh shell produces this error messages  not bash

[bash] String comparison in bash. [[: not found

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