a2p

a2p [options] [filename ...]

a2p reads the awk script from the specified filename(s) or from standard input if no files are provided, and writes the translated Perl script to standard output.

-D
    Enable debugging output. The number indicates the level of debugging information (e.g., 1, 2, 4, 8, 16).

-F
    Set the default field separator (equivalent to awk -F). The string can be a literal string or a regular expression.

-M
    Add use ; to the generated Perl script. Useful for including necessary Perl modules.

-n
    Do not assume awk style input parsing (i.e., do not automatically split lines into fields). This is useful when the awk script processes whole lines or uses getline extensively.

-N
    Assume awk style input parsing (this is the default behavior).

-o
    Optimize the generated Perl script. This might produce more concise or efficient Perl code.

-S
    Generate stricter Perl code, adding use strict; and use warnings; pragmas. This encourages better coding practices in the resulting script.

-C
    Include comments from the original awk script in the translated Perl script.

-v =
    Predefine an awk variable with a given value (equivalent to awk -v). Multiple -v options can be used.

-w
    Enable Perl warnings in the generated script (adds -w to the #!/usr/bin/perl line or use warnings;).

a2p is a utility that translates awk scripts into Perl scripts. Its primary purpose is to aid in migrating existing awk codebases to Perl, allowing developers to leverage Perl's more powerful features, extensive module ecosystem, and better performance for complex tasks. It attempts to translate common awk constructs such as BEGIN and END blocks, pattern-action pairs, built-in variables (e.g., NR, NF, FS), and functions (e.g., print, printf, gsub). While a2p does an admirable job for many straightforward awk scripts, the resulting Perl code may not always be idiomatic or fully optimized. Complex awk patterns, specific regular expression behaviors, or reliance on nuanced awk internals might require manual adjustments to the generated Perl script. Nonetheless, it provides a valuable starting point, significantly reducing the manual effort involved in such migrations.

While a2p is a powerful migration tool, it has several caveats:

• Not 100% Perfect: It cannot translate every conceivable awk script perfectly, especially those relying on very obscure awk features or highly specific regular expression nuances.
• Idiomatic Perl: The generated Perl code might not always be the most idiomatic or efficient Perl. It often reflects a direct translation rather than a redesign for Perl's strengths.
• Regular Expression Differences: Subtle differences in regular expression syntax or behavior between awk and Perl can lead to unexpected results.
• getline and File Handling: Complex awk scripts using getline or intricate file handling might require significant manual review and adjustment.
• Performance: While Perl is generally faster than awk for complex tasks, a directly translated script might not immediately outperform a well-optimized awk script without further Perl optimizations.

To convert a simple awk script:
# my_script.awk
BEGIN { print "Starting..." }
{ print NR, $0 }
END { print "Finished." }
You can translate it using:
a2p my_script.awk > my_script.pl
The generated my_script.pl will contain the Perl equivalent code.

To convert an awk script from standard input with a specific field separator:
echo '1:2:3' | a2p -F: '{ print NF, $1 }'
This would output the Perl code that, when run, would print '3 1'.

a2p is an integral part of the Perl distribution itself, signifying Perl's design philosophy as a superset and successor to traditional Unix text-processing tools like awk and sed. It was developed early in Perl's history to facilitate the migration of existing text-processing workflows from awk to Perl. This allowed users familiar with awk's pattern-action paradigm to transition more easily to Perl, which offered greater power, flexibility, and extensibility.

awk(1): The original text processing language from which a2p translates scripts., perl(1): The powerful scripting language that is the target of the translation., s2p(1): A similar utility for converting sed scripts to Perl scripts.