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erase content from a cdrw

list block devices
Shows all block devices in a tree with descruptions of what they are.

Backup a file with a date-time stamp
1. you don't need to prepend the year with 20 - just use Y instead of y 2. you may want to make your function a bit more secure: buf () { cp ${1?filename not specified}{,$(date +%Y%m%d_%H%M%S)}; }

Swap a file or dir with quick resotre
This lets you replace a file or directory and quickly revert if something goes wrong. For example, the current version of a website's files are in public_html. Put a new version of the site in public_html~ and execute the command. The names are swapped. If anything goes wrong, execute it again (up arrow or !!).

Retrieve "last modified" timestamp of web resource in UTC seconds
This command line assumes that "${url}" is the URL of the web resource. It can be useful to check the "freshness" of a download URL before a GET request.

Remove audio stream from a media file
This syntax also works for ffmpeg as avconv is a fork of ffmpeg.

prints message in given argument on on center of screen
$ function echox { echo `tput cup $(($(tput lines))) $(( ($(tput cols) - $(echo "${#1}"))/2 ))`"$1"`tput cup $(tput lines) $(( $(tput cols)-1 ))`; } echox prints given argument on bottom line center screen in terminal $ function echoxy { echo `tput cup $(($(tput lines)/2)) $(( ($(tput cols) - $(echo "${#1}"))/2))`"$1"`tput cup $(tput lines) $(( $(tput cols)-1 ))`; } exhoxy prints given argument center screen $ function echos { echo `tput cup $(($(tput lines)-2)) $(($(tput cols)-$(echo ${#1})))&&tput sc`"$1"`tput cup $(($(tput lines)-2)) 0 && tput rc`; } $ while [ 1 ]; do echos "`date`"; done echos prints date and time on second from last line (used as status message) you can easily use these functions by placing them in your .bashrc file, make sure to source your .bashrc once you do

Size(k) of directories(Biggest first)
somewhat faster version to see the size of our directories. Size will be in Kilo Bytes. to view smallest first change '-k1nr' to '-k1n'.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

export iPad App list to txt file
This will generate the same output without changing the current directory, and filepath will be relative to the current directory. Note: it will (still) fail if your iTunes library is in a non-standard location.


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