# http://programming.newsforge.com/comments.pl?sid=54523&cid=123985

# Pick a random file (e.g. MP3)
ls | perl -e '@a=<>;print $a[rand(@a)]'

# Shuffle the contents of a file
cat foo | perl -e '@a=<>;while(@a){print splice(@a,rand(@a),1)}'


# http://linuxgazette.net/issue85/okopnik.html

# A list of duplicate UIDs, along with their related usernames
# perl -F: -walne'$h{$F[2]}.="$F[0] ";END{$h{$_}=~/ ./&&print"$_: $h{$_}"for keys%h}' /etc/passwd

# the next available UID
perl -wle'{getpwuid++$n&&redo;print$n}'
# после 1000
perl -wle '$n=1000; {getpwuid ++$n && redo; print $n}'


# Удаление повторяющихся строк из файла
perl -i -ne '$s{$_}++ || print' file

# Удаление из файла строк с неуникальным первым полем
perl -i -ane '$s{$F[0]}++ || print' file

# Печатает номера повторяющихся строк файла
perl -lne '$s{$_}++ && print $.'  file


# Объединение файлов (с удалением неуникальных строк)
perl -ne '$s{$_}++ || print' file1 file2

# Пересечение файлов (с удалением неуникальных строк)
perl -ne '$s{$_}++ || print' file1 file2

# Симметричная разность файлов (не содержищих неуникальных строк)
# (a la Nab, http://forum.vingrad.ru/index.php?showtopic=111918&view=findpost&p=857611)
perl -e '$"=""; ($_="@{[sort(<>)]}")=~s/(.+\n)\1//g; print' file1 file2


# Perl Cookbook
# Поиск длинных палиндромов (слов, читаемых одинаково в обоих направлениях)
perl -nle 'print if $_ eq reverse && length >5' words


# http://ru.wikipedia.org/wiki/Perl
# печатаются простые числа
perl -wle '(1 x $_) !~ /^(11+)\1+$/ && print while ++ $_'


##############################################################################
# ftp://www6.software.ibm.com/software/developer/library/l-p102/tomc.txt

# run contents of "my_file" as a program
perl my_file

# run debugger "stand-alone"
perl -d -e 42

# run program, but with warnings
perl -w my_file

# run program under debugger
perl -d my_file

# just check syntax, with warnings
perl -wc my_file

# useful at end of "find foo -print"
perl -nle unlink

# simplest one-liner program
perl -e 'print "hello world!\n"'

# add first and penultimate columns
perl -lane 'print $F[0] + $F[-2]'

# just lines 15 to 17
perl -ne 'print if 15 .. 17' *.pod

# in-place edit of *.c files changing all foo to bar
perl -p -i.bak -e 's/\bfoo\b/bar/g' *.c

# command-line that prints the first 50 lines (cheaply) 
perl -pe 'exit if $. > 50' f1 f2 f3 ...

# delete first 10 lines
perl -i.old -ne 'print unless 1 .. 10' foo.txt

# change all the isolated oldvar occurrences to newvar
perl -i.old -pe 's{\boldvar\b}{newvar}g' *.[chy]

# command-line that reverses the whole file by lines
perl -e 'print reverse <>' file1 file2 file3 ....

# find palindromes
perl -lne 'print if $_ eq reverse' /usr/dict/words

# command-line that reverse all the bytes in a file
perl -0777e 'print scalar reverse <>' f1 f2 f3 ...

# command-line that reverses the whole file by paragraphs
perl -00 -e 'print reverse <>' file1 file2 file3 ....

# increment all numbers found in these files
perl i.tiny -pe 's/(\d+)/ 1 + $1 /ge' file1 file2 ....

# command-line that shows each line with its characters backwards
perl -nle 'print scalar reverse $_' file1 file2 file3 ....

# delete all but lines between START and END
perl -i.old -ne 'print unless /^START$/ .. /^END$/' foo.txt

# binary edit (careful!)
perl -i.bak -pe 's/Mozilla/Slopoke/g' /usr/local/bin/netscape

# look for dup words
perl -0777 -ne 'print "$.: doubled $_\n" while /\b(\w+)\b\s+\b\1\b/gi'

# command-line that prints the last 50 lines (expensively)
perl -e '@lines = <>; print @lines[ $#lines .. $#lines-50' f1 f2 f3 ...

##############################################################################

# http://www-128.ibm.com/developerworks/linux/library/l-p102.html

# add first and penultimate columns
# NOTE the equivalent awk script: 
# awk '{i = NF - 1; print $1 + $i}'
perl -lane 'print $F[0] + $F[-2]'

### Printing a range of lines
# 1. just lines 15 to 17
perl -ne 'print if 15 .. 17'

# 2. just lines NOT between line 10 and 20
perl -ne 'print unless 10 .. 20'

# 3. lines between START and END
perl -ne 'print if /^START$/ .. /^END$/'

# 4. lines NOT between START and END
perl -ne 'print unless /^START$/ .. /^END$/'

# just lines 15 to 17, efficiently
perl -ne 'print if $. >= 15; exit if $. >= 17;'

### In-place editing
# 1. in-place edit of *.c files changing all foo to bar
perl -p -i.bak -e 's/\bfoo\b/bar/g' *.c

# 2. delete first 10 lines
perl -i.old -ne 'print unless 1 .. 10' foo.txt

# 3. change all the isolated oldvar occurrences to newvar
perl -i.old -pe 's{\boldvar\b}{newvar}g' *.[chy]

# 4. increment all numbers found in these files
perl -i.tiny -pe 's/(\d+)/ 1 + $1 /ge' file1 file2 ....

# 5. delete all but lines between START and END
perl -i.old -ne 'print unless /^START$/ .. /^END$/' foo.txt

# 6. binary edit (careful!)
perl -i.bak -pe 's/Mozilla/Slopoke/g' /usr/local/bin/ne

### Reversal of files' fortunes
# 1. command-line that reverses the whole input by lines
#    (printing each line in reverse order)
perl -e 'print reverse <>' file1 file2 file3 ....

# 2. command-line that shows each line with its characters backwards
perl -nle 'print scalar reverse $_' file1 file2 file3 ....

# 3. find palindromes in the /usr/dict/words dictionary file
perl -lne '$_ = lc $_; print if $_ eq reverse' /usr/dict/words

# 4. command-line that reverses all the bytes in a file
perl -0777e 'print scalar reverse <>' f1 f2 f3 ...

# 5. command-line that reverses each paragraph in the file but prints
#    them in order
perl -00 -e 'print reverse <>' file1 file2 file3 ....

# replace string XYZ with a random number less than 611 in these files
perl -i.bak -pe "s/XYZ/int rand(611)/e" f1 f2 f3

### Revealing the files' base nature
# 1. Run basename on contents of file
perl -pe "s@.*/@@gio" INDEX

# 2. Run dirname on contents of file
perl -pe 's@^(.*/)[^/]+@$1\n@' INDEX

# 3. Run basename on contents of file
perl -MFile::Basename -ne 'print basename $_' INDEX

# 4. Run dirname on contents of file
perl -MFile::Basename -ne 'print dirname $_' INDEX

### Moving or renaming, it's all the same in UNIX
# 1. write command to mv dirs XYZ_asd to Asd
# (you may have to preface each '!' with a '\' depending on your shell)
ls | perl -pe 's!([^_]+)_(.)(.*)!mv $1_$2$3 \u$2\E$3!gio'

# 2. Write a shell script to move input from xyz to Xyz
ls | perl -ne 'chop; printf "mv $_ %s\n", ucfirst $_;'


# http://www-128.ibm.com/developerworks/linux/library/l-p101/
# Ничего особо интересного

# http://www.ajs.com/ajswiki/Perl_one-liners

# http://www.rollmop.org/oneliners/perl.html

# http://defindit.com/readme_files/perl_one_liners.html