mirror of
https://github.com/chubin/cheat.sheets
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51 lines
1.9 KiB
Plaintext
51 lines
1.9 KiB
Plaintext
# perl
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# The Perl 5 language interpreter.
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# Parse and execute a Perl script:
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perl script.pl
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# Check syntax errors on a Perl script:
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perl -c script.pl
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# Parse and execute a perl statement:
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perl -e perl_statement
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# Import module before execution of a perl statement:
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perl -Mmodule -e perl_statement
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# Run a Perl script in debug mode, using perldebug:
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perl -d script.pl
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# Loo[p] over all lines of a file, editing them [i]n-place using a find/replace [e]xpression:
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perl -p -i -e 's/find/replace/g' filename
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# Run a find/replace expression on a file, saving the original file with a given extension:
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perl -p -i'.old' -e 's/find/replace/g' filename
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# See also:
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# Perl language cheat sheets at /perl/
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# list of pages: /perl/:list
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# learn perl: /perl/:learn
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# perl one-liners: /perl/1line
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# search in pages: /perl/~keyword
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# Perl method of listing out the environment variables, sans values.
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perl -e 'print("$_\n") foreach keys(%ENV)'
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# Output the columns and lines of the current terminal.
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perl -e 'use Term::ReadKey "GetTerminalSize"; my ($Cols, $Lines) = GetTerminalSize(); print("${Cols}x$Lines\n")'
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# List out all of the aliases within the provided file. This works by iterating
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# over each line of the file, displaying only those lines matching the REGEX.
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# Before printing out the relevant lines, all tabs are removed.
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perl -ne '/^[[:space:]]+alias/ and print(tr/\t//dr)' "$HOME/.bash_aliases"
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# Alternative logic approach:
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perl -ne 'print(tr/\t//dr) if /^[[:space:]]+alias/' "$HOME/.bash_aliases"
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# See if the current user has a non-empty password value. This may not work for
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# systems set up with shadow passwords, however.
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perl -ne '/^$ARGV[0]::$</ and print(STDERR "WARNING: User has an empty password.\n")' /etc/passwd ichy
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# Display the current user's UID and GID in a format ideal for chmod(1).
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perl -e 'print("$<:" . (split(" ", $)))[0] . "\n")'
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