Delete whitespace in each begin of line of file, using bash

Question

How i can delete whitespace in each line of file, using bash For instance, file1.txt. Before:

  gg g
 gg g
t  ttt

after:

gg         


        

Answer 1

To delete the white spaces before start of the line if the pattern matches. Use the following command. For example your foo.in has pattern like this

      This is a test                                
                    Lolll
                       blaahhh
      This is a testtt

After issuing following command

sed -e '/This/s/ *//' < foo.in > foo.out

The foo.out will be

This is a test
             Lolll
                blaahhh
This is a testtt