Compare strings in shell script

Question

I have a file named parameters.txt whose contents are as follows:

sheet_name:TEST
sheet_id:CST
sheet_access:YES

And I have a shell script which fetches this text from the parameters.txt file. It uses : as a delimiter for each line of the parameters.txt file and stores whatever is left of : in var1 and whatever is right of : in var2. I want to print matched when var1 stores sheet_name and not matched when it doesn't stores sheet_name. Following is my code which always prints matched irrespective of what var1 stores:

filename=parameters.txt
IFS=$'\n'       # make newlines the only separator

for j in `cat $filename`
   do
      var1=${j%:*} # stores text before :
      var2=${j#*:} # stores text after :

      if [ “$var1” == “sheet_name” ]; then
         echo ‘matched’
      else
         echo “not matched“
      fi

done

What am I doing wrong? Kindly help.

Don't use a for loop here; read mywiki.wooledge.org/BashFAQ/001 — chepner
– chepner, Commented Aug 11, 2016 at 12:58
You should run your code through shellcheck.net to catch a few issues. Also read Don't Read Lines with For and Bash FAQ 001 to see how to properly read line-by-line/field-by-field data. — Etan Reisner
– Etan Reisner, Commented Aug 11, 2016 at 12:58
Also your quotes are "smart"/unicode quotes and those aren't at all what you want in a shell script. Ensure you are using standard ASCII double and single quotes. — Etan Reisner
– Etan Reisner, Commented Aug 11, 2016 at 12:58
I just ran your script and sample file-- it works fine. You shouldn't use a for loop, but it does work. I have a feeling it's your parameters.txt that has an issue. Do a file parameters.txt and see what the output is. — SaintHax
– SaintHax, Commented Aug 11, 2016 at 13:08
That would be just reading line by line. I need to extract the left side of : for each line too. — Rajarshi Sarkar
– Rajarshi Sarkar, Commented Aug 11, 2016 at 13:34

sjsam · Accepted Answer · 2016-08-11 13:57:59Z

1

You have useless use of cat. But how about some [ shell parameter expansion ] ?

while read line
do
 if [[ "${line%:*}" = "sheet_name" ]] #double quote variables deals word splitting
 then
  echo "matched"
 fi
done<parameters.txt

would do exactly what you're looking for.

Message for you

[ ShellCheck ] says,

"To read lines rather than words, pipe/redirect to a 'while read' loop."

^{Check [ this ] note from shellcheck.}

edited Aug 11, 2016 at 13:57

answered Aug 11, 2016 at 13:45

sjsam

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Comments

thirafael · Accepted Answer · 2016-08-11 13:10:04Z

0

How about this?

filename=parameters.txt

while IFS=: read -r first second; do 
  if [ “$first” == “sheet_name” ]; then 
     echo ‘matched’
  else  
     echo “not matched“ 
  fi 
done < $filename

answered Aug 11, 2016 at 13:10

thirafael

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1 Comment

Rajarshi Sarkar Over a year ago

Prints not matched for all cases.

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