How to align only one line in file to the left side with sed or perl one liner

Question

This will delete all spaces and tabs at the beginning of every line:

sed 's/^[ \t]*//' file

but lets say we want to align only the parameter queued.max.requests=1000 from file

• Example input:

      log.flush.interval.messages=20000
      queued.max.requests = 1000
      producer.purgatory.purge.interval.requests=100
  

• Desired output:

       log.flush.interval.messages=20000
  queued.max.requests=1000
       producer.purgatory.purge.interval.requests=100
  

How we can fit the sed 's/^[ \t]*//' for this case? Also, I want sed/perl to delete the spaces between the parameter to "=" and from "=" to the value in the process.

Answer 1

How about

sed '/queued\.max\.requests/s/[\t ]\{1,\}//g' file

or

sed -r '/queued\.max\.requests/s/[\t ]+//g' file

This will remove all space (from the beginning of the line, as well as that surrounding the =) from only the line containing queued.max.requests.

Answer 2

$ sed 's/^[[:space:]]*\(queued\.max\.requests\)/\1/; s/ *= */=/' file
    log.flush.interval.messages=20000
queued.max.requests=1000
    producer.purgatory.purge.interval.requests=100