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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" }

Bind a key with a command
the -x option is for binding to a shell command

Run a command after the process you choose finishes
Run a command as soon as another long-running command finishes. E.g. suspend the machine after performing apt upgrade. The process is selected interactively via fzf.

strip config files of comments
some configuration files, particularly those installed by default as part of a package, have tons of comment lines, to help you know what's possible to configure, and what it means. That's nice, but sometimes you just want to see what specifically what _has_ been configured. That's when I use the above snippet, which I save as a bash alias 'nocom' (for 'no comments'). Apache default config files are perfect examples of when/why this script is handy.

Start a quick rsync daemon for fast copying on internal secure network
"Sample output" shows a minimalistic configuration file.

Save an HTML page, and covert it to a .pdf file
Uses htmldoc to perform the conversion

Check a directory of PNG files for errors
Useful for checking if a large number of PNG files was downloaded successfully by verifying the built-in CRC checksum. For incomplete files, the command will print: "00002309.png EOF while reading IDAT data ERROR: 00002309.png" The process is very fast; checking 21,000 files of 5MB in size took only five minutes on a 2011 Intel mobile dual-core.

Calculating series with awk: add numbers from 1 to 100
"seq 100" outputs 1,2,..,100, separated by newlines. awk adds them up and displays the sum. "seq 1 2 11" outputs 1,3,..,11. Variations: 1+3+...+(2n-1) = n^2 $ seq 1 2 19 | awk '{sum+=$1} END {print sum}' # displays 100 1/2 + 1/4 + ... = 1 $ seq 10 | awk '{sum+=1/(2**$1)} END {print sum}' # displays 0.999023

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Install pip with Proxy
Installs pip packages defining a proxy


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