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check open ports without netstat or lsof

start a tunnel from some machine's port 80 to your local post 2001
now you can acces the website by going to http://localhost:2001/

Prepend a text to a file.
Using the sed -i (inline), you can replace the beginning of the first line of a file without redirecting the output to a temporary location.

Delete all non-printing characters from a file
tr has some predefined sets of characters that are more convenient to use than characters codes

list files recursively by size

Print all the lines between 10 and 20 of a file
Subtly different to the -n+p method... and probably wrong in so many ways....... But it's shorter. Just.

append empty line after every line in file.txt

Speed up builds and scripts, remove duplicate entries in $PATH. Users scripts are oftern bad: PATH=/apath:$PATH type of thing cause diplicate.
Thanks to the authors of: $ awk '!x[$0]++' and the author of: $ joinargs() { (local IFS="$1"; shift && echo "$*") } and others, we can have a fast Linux or android. IMPORTANT if you find a priority order problem in PATH you can push a path directory to the front without duplication as follows: $ PATH=/bin:$PATH then ... Check duplication with: $ echo $PATH|tr : '\n'|sort|uniq -d Finally do a very neat line by line list of $PATH: $ echo "${PATH//:/$'\n'} The speed up is very noticeable for android, and builds on Linux Ubantu are much faster with make and scripts. I will update the command on request. Timothy from SONY

Output entire line once per unique value of the first column
Removes duplicates in the specified field/column while outputting entire lines. An elegant command for processing tab (or otherwise) delimited data.

watch process stack, sampled at 1s intervals
This command repeatedly gets the specified process' stack using pstack (which is an insanely clever and tiny wrapper for gdb) and displays it fullscreen. Since it updates every second, you rapidly get an idea of where your program is stuck or spending time. The 'tac' is used to make the output grow down, which makes it less jumpy. If the output is too big for your screen, you can always leave the 'tac' off to see the inner calls. (Or, better yet--get a bigger screen.) Caveats: Won't work with stripped binaries and probably not well with threads, but you don't want to strip your binaries or use threads anyway.


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