Perl

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Perl one liners

If you type;

perl --help

on the command line, Perl will provide details on its usage and command line switches. The switches we are interested in are

  -d[:debugger]   run program under debugger
  -e program      one line of program (several -e's allowed, omit programfile)
  -n              assume 'while (<>) { ... }' loop around program

Using -e switch

# Unix/Linux
perl -e 'print "It matches\n" if "Hello World" =~ /World/;'
# Windows
perl -e "print \"It matches\n\" if "Hello World" =~ /World/;"

• See string literals for details on differences between single and double quotes.

Using -de switch

To initiate the debugger for a one line program type;

perl -de 42

Now type 'h' to obtain for help commands used within the debugger. Commands useful for one liners in the debugger are;

• 'x' to eval an expression in list context, and print the result.
• 'q' to quit

See also

• Our Perl scripts
• Date formatting symbols
• Basic DBI tutorial
• Regular expressions and Quotemeta
• Reading and writing UTF-8 examples with IO::All