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2011-03-12 - Confoo 2011 presentation
Slides are available from the commandlinefu presentation at Confoo 2011: http://presentations.codeinthehole.com/confoo2011/
2011-01-04 - Moderation now required for new commands
To try and put and end to the spamming, new commands require moderation before they will appear on the site.
2010-12-27 - Apologies for not banning the trolls sooner
Have been away from the interwebs over Christmas. Will be more vigilant henceforth.
2010-09-24 - OAuth and pagination problems fixed
Apologies for the delay in getting Twitter's OAuth supported. Annoying pagination gremlin also fixed.




Commands by flatcap from sorted by
Terminal - Commands by flatcap - 35 results
find . -type f -newermt "2010-01-01" ! -newermt "2010-06-01"
2011-06-26 09:52:26
User: flatcap
Functions: find
Tags: find dates

Find files in a specific date range - in this case, the first half of last year.

-newermt = modification time of the file is more recent than this date

GNU find allows any date specfication that GNU date would accept, e.g.

find . -type f -newermt "3 years ago" ! -newermt "2 years ago"


find . -type f -newermt "last monday"
cd() { if [ -n "$1" ]; then [ -f "$1" ] && set -- "${1%/*}"; else [ -n "$CDDIR" ] && set -- "$CDDIR"; fi; command cd "$@"; }
2011-06-24 08:48:13
User: flatcap
Functions: cd command set
Tags: cd test set

Move efficiently between directories.


This command adds a couple of extra features to cd, without affecting normal use.

CDPATH use is also unaffected. It introduces and environment variable CDDIR which is used as an alternate home directory.


Note: I don't want to alter $HOME because then all my dot files will move.




cd dir

Change directory to "dir" (using CDPATH if necessary)


cd dir/file.txt

Change directory to "dir" (containing folder of "file.txt")

This allows you to cut'n'paste, or use


CDDIR is unset


Change directory to $HOME




Change directory to /home/flatcap/work


For convenience, put the command, and the following, in your .bashrc or .bash_profile

export CDDIR="/home/flatcap/work"

alias cdd="CDDIR=$(pwd)"

rf() { for i in "$@"; do mv "$i" "$(pwgen 8 1).${i##*.}"; done }
2011-06-22 07:45:23
User: flatcap
Functions: mv

Give files a random name (don't ask why :-)

The function will rename files but maintain their extensions.

BUG: If a file doesn't have an extension it will end up with a dot at the end of the name.

The parameter '8' for pwgen controls the length of filenames - eight random characters.

find . -type f -name \*.php | while IFS="" read i; do expand -t4 "$i" > "$i-"; mv "$i-" "$i"; done
2011-04-08 12:53:14
User: flatcap
Functions: expand find mv read

Recursively find php files and replace tab characters with spaces.


"\*.php" -- replace this with the files you wish to find

"expand" -- replace tabs with spaces (use "unexpand" to replace spaces with tabs)

"-t4" -- tabs represent 4 spaces

Note: The IFS="" in the middle is to prevent 'read' from eating leading/trailing whitespace in filenames.

ls -1 | sort -R | sed -n 's/^/Selected /;1p'
MIN=10;for ((i=MIN*60;i>=0;i--));do echo -ne "\r$(date -d"0+$i sec" +%H:%M:%S)";sleep 1;done
2011-02-20 11:56:28
User: flatcap
Functions: echo sleep

Countdown clock - Counts down from $MIN minutes to zero.

I let the date command do the maths.

This version doesn't use seq.

s(){ sed 's/./\n\0/g'<<<$1|sort;};cmp -s <(s foobar) <(s farboo)||echo -n "not ";echo anagram
2011-02-17 12:42:45
User: flatcap
Functions: cmp echo sed

Are the two strings anagrams of one another?

sed splits up the strings into one character per line

the result is sorted

cmp compares the results

Note: This is not pretty. I just wanted to see if I could do it in bash.

Note: It uses fewer characters than the perl version :-)

files -type f | xargs -n100 | while read l; do mkdir $((++f)); cp $l $f; done
2011-02-15 23:15:16
User: flatcap
Functions: cp mkdir read xargs

Take a folder full of files and split it into smaller folders containing a maximum number of files. In this case, 100 files per directory.

find creates the list of files

xargs breaks up the list into groups of 100

for each group, create a directory and copy in the files

Note: This command won't work if there is whitespace in the filenames (but then again, neither do the alternative commands :-)

for((r=1;r<10;r++));do v=1;echo -n "$v ";for((c=1;c<$r;c++));do v2=$(($(echo "$v*($r-$c)/$c")));echo -n "$v2 ";v=$v2;done;echo;done
2011-02-10 18:38:04
User: flatcap
Functions: echo
Tags: bash math


This one's for bartonski. Enjoy.

132 characters. I'm sure we can do better.

Note: after row 64 we overflow integer maths.

seq 1 2 99999999 | sed 's!^!4/!' | paste -sd-+ | bc -l
2011-02-09 23:36:07
User: flatcap
Functions: bc paste sed seq
Tags: sed seq bc paste math

Calculate pi from the infinite series 4/1 - 4/3 + 4/5 - 4/7 + ...

This expansion was formulated by Gottfried Leibniz: http://en.wikipedia.org/wiki/Leibniz_formula_for_pi

I helped rubenmoran create the sum of a sequence of numbers and he replied with a command for the sequence: 1 + 2 -3 + 4 ...

This set me thinking. Transcendental numbers!

seq provides the odd numbers 1, 3, 5

sed turns them into 4/1 4/3 4/5

paste inserts - and +

bc -l does the calculation

Note: 100 million iterations takes quite a while. 1 billion and I run out of memory.