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May 19, 2015 - A Look At The New Commandlinefu
I've put together a short writeup on what kind of newness you can expect from the next iteration of clfu. Check it out here.
March 2, 2015 - New Management
I'm Jon, I'll be maintaining and improving clfu. Thanks to David for building such a great resource!

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Commands using comm from sorted by
Terminal - Commands using comm - 8 results
comm -13 <(od -vw1 -tu1 dummy.txt|cut -c9-|sort -u) <(seq 0 127|sort)|perl -pe '$_=chr($_)'|od -c
2012-01-09 01:32:20
User: bazzargh
Functions: comm cut od perl seq sort
Tags: bash

Search in decimal rather than hex. od dumps the character list, cut to remove offsets, sort -u gives the used characters. seq gives the comparison list, but we need this sorted alphabetically for comm, which does the filtering. I drop to perl to convert back to characters (is there a better way?) and then use od to dump them in a print-safe format.

comm -13 <(sort file1) <(sort file2) > file-new
2011-10-01 18:07:54
User: daa
Functions: comm sort

If both file1 and file2 are already sorted:

comm -13 file1 file2 > file-new

awk -F" " '{ if ( NF == 1 ) { print $0 } }' KINDLE_NOTES_FILE.txt | sed -e '/^=/d' | sed -e '/^[[:space:]]*$/d' -e 's/,//g' | sort | comm -12 List_of_language_words.txt - | uniq
2011-08-15 14:35:33
User: parmegv
Functions: awk comm sed sort

You can use any dictionary you want, in any language.

This command will output all single-word annotations that you have underlined in your Kindle device (provided the file) given a list of language-specific words.

If you want to learn vocabulary, this command is ideal.

comm -12 FILE1.sorted FILE2.sorted > common
comm --nocheck-order -31
Array1=( "one" "two" "three" "four" "five" );Array2=( "four" "five" "six" "seven" );savedIFS="${IFS}";IFS=$'\n';Array3=($(comm -12 <(echo "${Array1[*]}" |sort -u) <(echo "${Array2[*]}" | sort -u)));IFS=$savedIFS
2010-08-23 19:25:22
User: elofland
Functions: comm echo sort

the comm utility (opposite of diff) show commonalities in files (in this case strings)

comm file1 file2 | sed -e 's/^[^\t].*/\x1b[33m&\x1b[0m/' -e 's/^\t[^\t].*/\x1b[36m&\x1b[0m/' -e 's/^\t\t[^\t].*/\x1b[32m&\x1b[0m/'
2010-05-07 00:14:31
User: recursiverse
Functions: comm sed

It just colorizes the line based on if it has 0, 1 or 2 tabs at the beginning of the line. Won't work so well if lines already begin with tabs (too bad comm doesn't have an option to substitute \t for something else).

Don't forget comm needs input files to be sorted. You can use a shortcut like this with bash: comm

comm -1 -2 <(sort file1) <(sort file2)