Question

how to shift the top element from array based on a regular expression using perl? Also these are datarecords, meaning I have the input record separator ($/) set to

$/=’#’;

for example, the following text file contains this data record.

    #dddddddddd
    ccccccccccc
    eeeeeeeeeee
    fffffffffff

I would like to remove the # sign and keep the text, for example:

    dddddddddd
    ccccccccccc
    eeeeeeeeeee
    fffffffffff

Answer 1

If you just want to manipulate a text file, a one-liner seems like the best solution. This will edit the file and keep a backup in “inputfile.txt.bak”.

perl -pi.bak -we 's/^#//' inputfile.txt

Or you can do a shell redirection:

perl -wpe 's/^#//' inputfile.txt > outputfile.txt

These will try to alter all the lines in the file. If you just want the first line altered you need something different:

perl -wpe 's/^#// if ($. == 0);' inputfile.txt > outputfile.txt