Commands by gander (1)

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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

Rename files in batch

Create a simple video contact sheet using the vcs bash script
Assumes you've downloaded Toni Corvera's vcs script (http://p.outlyer.net/vcs), have it in your PATH, and have installed the script's dependencies. Generates a video contact sheet of 24 thumbnails and 3 thumbnails per column. The bold font and white-on-black color scheme keeps the text readable at the chosen 70% JPEG compression quality, which keeps the file size at a manageable level. You can go even lower with the quality and get a good looking result.

Push a directory onto the stack
Use also with: Move to respective parameters == () { = +2; } === () { = +3; } ==== () { = +4; } Pop the last entry off the directory stack - () { popd ${1:+"$1"}; }

Find all dot files and directories

Create a bash script from last commands
In order to write bash-scripts, I often do the task manually to see how it works. I type ### at the start of my session. The function fetches the commands from the last occurrence of '###', excluding the function call. You could prefix this with a here-document to have a proper script-header. Delete some lines, add a few variables and a loop, and you're ready to go. This function could probably be much shorter...

Recompress all text files in a subdirectory with lzma
This will deal nicely with filenames containing newlines and will run one lzma process per CPU core. It requires GNU Parallel http://www.youtube.com/watch?v=OpaiGYxkSuQ

Report the established connections for a particular port

send file to remote machine and unzip using ssh
This version transfers gzipped data which is unzipped as it arrives at the remote host.

Check if your desired password is already available in haveibeenpwnd database. This command uses the API provided by HIBP

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