offset: Indent Text (Unix Power Tools, 3rd Edition)

21.7. offset: Indent Text

Do you have a printer that starts each line too close to the left margin? You might want to indent text to make it look better on the screen or a printed page. Here's a Perl script that does that. It reads from files or standard input and writes to standard output. The default indentation is 5 spaces. For example, to send a copy of a file named graph to the lp printer, indented 12 spaces:

% offset -12 graph | lp

Here's the Perl script that does the job:

Go to http://examples.oreilly.com/upt3 for more information on: offset

#!/usr/local/bin/perl

if ($ARGV[0] =~ /-[0-9]+/) {
    ($indent = $ARGV[0]) =~ s/-//;
    shift @ARGV;
} else {
    $indent = 5;
}

while (<>) {
    print " " x $indent, $_;
}

If there's an indentation amount in the first command-line argument, the dash is stripped and the value stored, then that argument is shifted away. Then a loop steps through the remaining arguments, if any (otherwise standard input is read) and outputs their text preceded by spaces. The script uses the Perl operator "string" x n, which outputs the string (in this case, a single space) n times. The Perl $_ operator contains the current input line.

-- JP


21.6. Low-Level File Butchery with dd		21.8. Centering Lines in a File