NAME

pl - Swiss Army Knife of Perl One-Liners

SYNOPSIS

Just one small script extends perl -E with many bells & whistles: Various one-letter commands & magic variables (with meaningful aliases too) and more nifty loop options take Perl programming to the command line. List::Util is fully imported. Unless you pass a program on the command line, starts a simple Perl Shell.

How to e(cho) values, including from @A(RGV), with single $q(uote) & double $Q(uote). Same for hard-to-print values:

pl 'e "${q}Perl$q", "$Q@A$Q"' one liner
pl 'e \"Perl", \@A, undef' one liner

Print up to 3 matching lines, resetting count (and $.) for each file:

pl -rP3 '/Perl.*one.*liner/' file1 file2 file3

Loop over args, printing each with line ending. And same, shouting:

pl -opl '' Perl one liner
pl -opl '$_ = uc' Perl one liner

Count hits in magic statistics hash %n(umber):

pl -n '++$n{$1} while /(Perl|one|liner)/g' file1 file2 file3

Even though the point here is to make things even easier, most Perl one-liners from the internet work, just by omitting -e or -E. Known minor differences are: don't goto LINE, but next LINE is fine. In -n last goes straight to the next file instead of being like exit. And shenanigans with unbalanced braces won't work.

DESCRIPTION

Pl follows Perl's philosophy for one-liners: the one variable solely used in one-liners, @F, is single-lettered. Because not everyone may like that, Pl has it both ways. Everything is aliased both as a word and as a single letter, including Perl's own @F & *ARGV.

-b doesn't do a BEGIN block. Rather it is in the same scope as your main PERLCODE. So you can use it to initialise my variables. Whereas, if you define a my variable in a -n, -p, -o or -O loop, it's a new variable each time. This echoes "a c" because -e does do an END block, which is a closure of the first $inner variable:

pl -Ob 'my $outer'  -e 'echo $inner, $outer'  'my $inner = $outer = $ARGV' a b c
pl -Ob 'my $outer'  -e 'e $inner, $outer'  'my $inner = $outer = $A' a b c

diff | d { ... }

Multifile diff on unique key fields. If you have Algorithm::Diff with color highlighting.

Sorting

Hashes are sorted numerically at the end, if unambiguously possible. That is if either all numbers are unsigned hex (including undescores) or all numbers are valid Perl literals or all numbers are decimal as Perl parses them from strings (including leading zeroes). Otherwise, or if several keys have the same numeric value (e.g. 8, +8, 8e0, 0b100, 0B1_00, 010, 0x8), sorting is textual.

Detecting hex numbers sorts wrongly if you only have words like "babe", "bad" & "be". If you still do other numbers including 0xabc, you can turn it off by:

$sort_hex = 0;
$H = 0;

If you want strictly text sorting only:

$sort_txt = 1;
$H = 1;

EXAMPLES

Only some of these are original. But many have been adapted from the various Perl one-liner pages on the internet. This is no attempt to appropriate ownership, just to show how things are even easier and more concise with pl.

Looking at Perl

VERSION of a File

pl -P1 's/.+\bVERSION\s*=\s*[v$Quote$quote]([0-9.]+).+/$1/' pl
pl -P1 's/.+\bVERSION\s*=\s*[v$Q$q]([0-9.]+).+/$1/' pl

pl -rP1 's/.+\bVERSION\s*=\s*[v$Quote$quote]([0-9.]+).+/$ARGV: $1/' *.pm
pl -rP1 's/.+\bVERSION\s*=\s*[v$Q$q]([0-9.]+).+/$A: $1/' *.pm

Only POD or non-POD

You can extract either parts of a Perl file, with these commands. Note that they don't take the empty line before into account. If you want that, and you're sure the files adheres strictly to this convention, use the option -00P instead. If you want only the 1st POD (e.g. NAME & SYNOPSIS) use the option -P1 or -00P1:

pl -P '/^=\w/../^=cut/' file
pl -P 'not /^=\w/../^=cut/' file

Content of a Package

Pl's echo or e can print any item. Packages are funny hashes, with two colons at the end. Backslashing the variable passes it as a unit to Data::Dumper. Otherwise all elements would come out just separated by spaces:

pl 'echo \%List::Util::'
pl 'e \%List::Util::'

Library Loading

Where does perl load from, and what exactly has it loaded?

pl 'echo \@INC, \%INC'
pl 'e \@INC, \%INC'

Same, for a different Perl version, e.g. if you have perl5.20.0 in your path:

pl -V5.20.0 'echo \@INC, \%INC'
pl -V5.20.0 'e \@INC, \%INC'

Configuration

You get %Config::Config loaded on demand and returned by config or c:

pl 'echo config'
pl 'e c'

It returns a hash reference, from which you can lookup an entry:

pl 'echo config->{sitelib}'
pl 'e c->{sitelib}'

You can also return a sub-hash, of only the keys matching any regexps you pass:

pl 'echo config "random", qr/stream/'
pl 'e c qr/random/, "stream"'

File statistics

Count files per suffix

Find and pl both use the 0 option to allow funny filenames, including newlines. Sum up encountered suffixes in sort-value-numerically-at-end hash %number or %n:

find -print0 |
    pl -0ln '++$number{/(\.[^\/.]+)$/ ? $1 : "none"}'
find -print0 |
    pl -0ln '++$n{/(\.[^\/.]+)$/ ? $1 : "none"}'

Count files per directory per suffix

Match to last / & after a dot following something, i.e. not just a dot-file. "" is the suffix for suffixless files. Stores in sort-by-key-and-stringify-at-end %string or %s. So count in a nested hash of directory & suffix:

find -type f -print0 |
    pl -0ln '/^(.+)\/.+?(?:\.([^.]*))?$/; ++$string{$1}{$2}'
find -type f -print0 |
    pl -0ln '/^(.+)\/.+?(?:\.([^.]*))?$/; ++$s{$1}{$2}'

This is the same, but groups by suffix and counts per directory:

find -type f -print0 |
    pl -0ln '/^(.+)\/.+?(?:\.([^.]*))?$/; ++$string{$2}{$1}'
find -type f -print0 |
    pl -0ln '/^(.+)\/.+?(?:\.([^.]*))?$/; ++$s{$2}{$1}'

This is similar, but stores in sort-by-number-at-end %n. Since this matches suffixes optionally, a lone dot indicates no suffix. The downside is that it is neither sorted by directory, nor by suffix:

find -type f -print0 |
    pl -0ln '/^(.+)\/.+?(?:\.([^.]*))?$/; ++$n{"$1 .$2"}'

This avoids the lone dot:

find -type f -print0 |
    pl -0ln '/^(.+)\/.+?(?:\.([^.]*))?$/; ++$n{length($2) ? "$1 .$2" : "$1 none"}'

Sum up file-sizes per suffix.

Find separates output with a dot and -F splits on that. The \\ is to escape one backslash from the Shell. No matter how many dots the filename contains, 1st element is the size and last is the suffix. Sum it in %n, which gets sorted numerically at the end:

find -name '*.*' -type f -printf "%s.%f\0" |
    pl -0lanF\\. '$n{".$F[-1]"} += $F[0]'

This is similar, but also deals with suffixless files:

find -type f -printf "%s.%f\0" |
    pl -0lanF\\. '$n{@F == 2 ? "none" : ".$F[-1]"} += $F[0]'

Count files per date

Incredibly, find has no ready-made ISO date, so specify the 3 parts. If you don't want days, just leave out -%Td. Sum up encountered dates in sort-value-numerically-at-end hash %number or %n:

find -printf '%TY-%Tm-%Td\n' |
    pl -ln '++$number{$_}'
find -printf '%TY-%Tm-%Td\n' |
    pl -ln '++$n{$_}'

Count files per date with rollup

todo Rollup means, additionally to the previous case The trick here is to count both for the actual year, month and day, as well as replacing once only the day, once also the month with "__",and once also the year with "____". This sorts after numbers and gives a sum for all with the same leading numbers.

find -printf '%TY-%Tm-%Td\n' |
    pl -ln '++$string{$_}; ++$string{$_} while s/[0-9]+(?=[-_]*$)/"_" x length $&/e'
find -printf '%TY-%Tm-%Td\n' |
    pl -ln '++$s{$_}; ++$s{$_} while s/[0-9]+(?=[-_]*$)/"_" x length $&/e'

Diff several files by a unique key

The function diff or d fills %d keyed by what you return and the arg counter $I. At the end only the rows differing between files are shown. If you have Algorithm::Diff the exact difference gets colour-highlighted.

Diff several csv, tsv or passwd files by 1st field

This assumes no comma in key field and no newline in any field. Else you need a csv-parser package:

pl -anF, 'diff { $FIELD[0] }' *.csv
pl -anF, 'd { $F[0] }' *.csv

This is similar, but removes the key from the stored value, so it doesn't get repeated for each file:

pl -n 'diff { s/(.+?),//; $1 }' *.csv
pl -n 'd { s/(.+?),//; $1 }' *.csv

A variant of csv is tsv, with tab as separator. Tab is \t, which must be escaped from the Shell as \\t:

pl -anF\\t 'diff { $FIELD[0] }' *.tsv
pl -anF\\t 'd { $F[0] }' *.tsv
pl -n 'diff { s/(.+?)\t//; $1 }' *.tsv
pl -n 'd { s/(.+?)\t//; $1 }' *.tsv

The same, with a colon as separator, if you want to compare passwd files from several hosts:

pl -anF: 'diff { $FIELD[0] }' /etc/passwd passwd*
pl -anF: 'd { $F[0] }' /etc/passwd passwd*
pl -n 'diff { s/(.+?)://; $1 }' /etc/passwd passwd*
pl -n 'd { s/(.+?)://; $1 }' /etc/passwd passwd*

Diff several zip archives by member name

This uses the same mechanism as the csv example. Addidionally it reads the output of unzip -vql for each archive through the pipe or p block. That has a fixed format, except for tiny members, which can report -200%, screwing the column by one:

pl -o 'piped { diff { s/^.{56,57}\K  (.+)//; $1 } if / Defl:/ } "unzip", "-vql", $_' *.zip
pl -o 'p { d { s/^.{56,57}\K  (.+)//; $1 } if / Defl:/ } "unzip", "-vql", $_' *.zip

If you do a clean build of java, many class files will have the identical crc, but still differ by date. This excludes the date:

pl -o 'piped { diff { s/^.{31,32}\K.{16} ([\da-f]{8})  (.+)/$1/; $2 } if / Defl:/ } "unzip", "-vql", $_' *.jar
pl -o 'p { d { s/^.{31,32}\K.{16} ([\da-f]{8})  (.+)/$1/; $2 } if / Defl:/ } "unzip", "-vql", $_' *.jar

Diff several tarballs by member name

This is like the zip example. But tar gives no checksum, so this is not very reliable. Each time a wider file size was seen columns shift right. Reformat the columns, so this doesn't show up as a differenceq:

pl -o 'piped { diff { s/^\S+ \K(.+?) +(\d+) (.{16}) (.+)/sprintf "%-20s %10d %s", $1, $2, $3/e; $4 }} "tar", "-tvf", $_' *.tar *.tgz *.txz
pl -o 'p { d { s/^\S+ \K(.+?) +(\d+) (.{16}) (.+)/sprintf "%-20s %10d %s", $1, $2, $3/e; $4 }} "tar", "-tvf", $_' *.tar *.tgz *.txz

Again without the date:

pl -o 'piped { diff { s/^\S+ \K(.+?) +(\d+) .{16} (.+)/sprintf "%-20s %10d", $1, $2/e; $3 }} "tar", "-tvf", $_' *.tar *.tgz *.txz
pl -o 'p { d { s/^\S+ \K(.+?) +(\d+) .{16} (.+)/sprintf "%-20s %10d", $1, $2/e; $3 }} "tar", "-tvf", $_' *.tar *.tgz *.txz

Diff ELF executables or libraries by loaded dependencies

You get the idea: you can do this for any command that outputs records with a unique key. This one looks at the required libraries and which file they came from. For a change loop with -O and @A(RGV) to avoid the previous examples' confusion between outer $_ which are the cli args, and the inner one, which are the read lines:

pl -O 'piped { diff { $1 } if s/^\t(.+\.so.*) => (.*) \(\w+\)/$2/ } ldd => $ARGV' exe1 exe2 exe3
pl -O 'p { d { $1 } if s/^\t(.+\.so.*) => (.*) \(\w+\)/$2/ } ldd => $A' exe1 exe2 exe3

It's even more useful if you use just the basename as a key, because version numbers may change:

pl -O 'piped { diff { $2 } if s/^\t((.+)\.so.* => .*) \(\w+\)/$1/ } ldd => $ARGV' exe1 exe2 exe3
pl -O 'p { d { $2 } if s/^\t((.+)\.so.* => .*) \(\w+\)/$1/ } ldd => $A' exe1 exe2 exe3

Tables

ANSI foreground;background colour table

How to generate a table, hardly a one-liner... You get numbers to fill into "\e[FGm", "\e[BGm" or "\e[FG;BGm" to get a colour and close it with "\e[m". There are twice twice 8 different colors for dim & bright and for foreground & background. Hence the multiplication of escape codes and of values to fill them.

This fills @A(RGV) in -b, as though it had been given on the command line. It maps it to the 16fold number format to print the header. Then the main PERLCODE loops over it with $A (alias to $ARGV), thanks to -O, to print the body. All numbers are duplicated with (N)x2, once to go into the escape sequence, once to be displayed:

pl -Ob '@A = map +($_, $_+8), 1..8; f "co:  fg;bg"."%5d"x16, @A' \
    'f "%2d:  \e[%dm%d;   ".("\e[%dm%4d "x16)."\e[m", $A, ($A + ($A > 8 ? 81 : 29))x2, map +(($_)x2, ($_+60)x2), 40..47'

This does exactly the same, but explicitly loops over lists @co & @bg:

pl '@co = map +($_, $_+8), 1..8; @bg = map +(($_)x2, ($_+60)x2), 40..47;
    f "co:  fg;bg"."%5d"x16, @co;
    f "%2d:  \e[%dm%d;   ".("\e[%dm%4d "x16)."\e[m", $_, ($_ + ($_ > 8 ? 81 : 29))x2, @bg for @co'

Miscellaneous

Split up numbers with commas, dots or underscores

Loop and print with line-end (-opl) over remaining args in $_. If reading from stdin, instead of arguments, use only -pl. After a decimal dot, insert a comma before each 4th comma-less digit. Then do the same backwards from end or decimal dot:

pl -opl '1 while s/[,.]\d{3}\K(?=\d)/,/; 1 while s/\d\K(?=\d{3}(?:$|[.,]))/,/' \
    12345678 123456789 1234567890 1234.5678 3.141 3.14159265358

The same for languages with a decimal comma, using either a dot or a space as spacer:

pl -opl '1 while s/[,.]\d{3}\K(?=\d)/./; 1 while s/\d\K(?=\d{3}(?:$|[.,]))/./' \
    12345678 12345678 1234567890 1234,5678 3,141 3,141592653589
pl -opl '1 while s/[, ]\d{3}\K(?=\d)/ /; 1 while s/\d\K(?=\d{3}(?:$|[ ,]))/ /' \
    12345678 12345678 1234567890 1234,5678 3,141 3,141592653589

The same for Perl style output:

pl -opl '1 while s/[._]\d{3}\K(?=\d)/_/; 1 while s/\d\K(?=\d{3}(?:$|[._]))/_/' \
    12345678 123456789 1234567890 1234.5678 3.141 3.14159265358

DNS lookup

The h(osts) function deals with the nerdy gethost... etc. and outputs as a hosts file. The file is sorted by address type (localhost, link local, private, public), version (IPv4, IPv6) and address. You tack on any number of IP-addresses or hostnames, either as Perl arguments or on the command-line via @A(RGV):

pl 'hosts qw(perl.org 127.0.0.1 perldoc.perl.org cpan.org)'
pl 'hosts @ARGV' perl.org 127.0.0.1 perldoc.perl.org cpan.org
pl 'h qw(perl.org 127.0.0.1 perldoc.perl.org cpan.org)'
pl 'h @A' perl.org 127.0.0.1 perldoc.perl.org cpan.org

If you don't want it to be sorted, call h(osts) for individual addresses:

pl 'h for qw(perl.org 127.0.0.1 perldoc.perl.org cpan.org)'
pl -o h perl.org 127.0.0.1 perldoc.perl.org cpan.org

To install App::pl, copy and paste the appropriate command in to your terminal.

cpanm

cpanm App::pl

CPAN shell

perl -MCPAN -e shell
install App::pl

For more information on module installation, please visit the detailed CPAN module installation guide.

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