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concatenate avi files
concatenates avi files

Efficient count files in directory (no recursion)
$ time perl -e 'if(opendir D,"."){@a=readdir D;print $#a - 1,"\n"}' 205413 real 0m0.497s user 0m0.220s sys 0m0.268s $ time { ls |wc -l; } 205413 real 0m3.776s user 0m3.340s sys 0m0.424s ********* ** EDIT: turns out this perl liner is mostly masturbation. this is slightly faster: $ find . -maxdepth 1 | wc -l sh-3.2$ time { find . -maxdepth 1|wc -l; } 205414 real 0m0.456s user 0m0.116s sys 0m0.328s ** EDIT: now a slightly faster perl version $ perl -e 'if(opendir D,"."){++$c foreach readdir D}print $c-1,"\n"' sh-3.2$ time perl -e 'if(opendir D,"."){++$c foreach readdir D}print $c-1,"\n"' 205414 real 0m0.415s user 0m0.176s sys 0m0.232s

Show bz compressed PF binary log

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Get all the keyboard shortcuts in screen
Displays a list of all the basic keyboard shortcuts in screen.

Create Solid Archive (best compression) with 7z
Creates a solid archive with the highest possible compression (Ultra). Advantage of 7z is that it will use all the processor cores to create the archive. (Ok. at least version 9.04 does)

Display condensed log in a tree-like format.
Display condensed log in a tree-like format.

Get the full path of a bash script's Git repository head.
Rather than complicated and fragile paths relative to a script like "../../other", this command will retrieve the full path of the file's repository head. Safe with spaces in directory names. Works within a symlinked directory. Broken down: $cd "$(dirname "${BASH_SOURCE[0]}")" temporarily changes directories within this expansion. Double quoted "$(dirname" and ")" with unquoted ${BASH_SOURCE[0]} allows spaces in the path. $git rev-parse --show-toplevel gets the full path of the repository head of the current working directory, which was temporarily changed by the "cd".

underscore to camelcase

Download a new release of a program that you already have very quickly
Zsync is an implementation of rsync over HTTP that allows updating of files from a remote Web server without requiring a full download. For example, if you already have a Debian alpha, beta or RC copy downloaded, zsync can just download the updated bits of the new release of the file from the server. This requires the distributor of the file to have created a zsync build control file (using zsyncmake).


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