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Force the script to be started as root
Place this code at the beginning of your script to ensure that it can only be executed by the root.

Determining the excat memory usages by certain PID
this command gives you the total number of memory usuage and open files by the perticuler PID.

find out which directory uses most inodes - list total sum of directoryname existing on filesystem

apt-get via sudo
An apt-get wrapper function which will run the command via sudo, but will run it normally if you're only downloading source files. This was a bit of an excuse to show off the framework of $ cmd && echo true || echo false ...but as you can see, you must be careful about what is in the "true" block to make sure it executes without error, otherwise the "false" block will be executed. To allow the apt-get return code to pass through, you need to use a more normal if/else block: $ apt-get () { if [ "$1" = source ]; then command apt-get "$@"; else sudo apt-get "$@"; fi }

View the latest astronomy picture of the day from NASA.
Substitute feh for the image viewer of your choice. display (part of imagemagick) seems to be a popular choice.

calulate established tcp connection of local machine

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" }

Renaming a file without overwiting an existing file name
Sometimes in a hurry you may move or copy a file using an already existent file name. If you aliased the cp and mv command with the -i option you are prompted for a confirmation before overwriting but if your aliases aren't there you will loose the target file! The -b option will force the mv command to check if the destination file already exists and if it is already there a backup copy with an ending ~ is created.

Check tcp-wrapping support
This function returns TRUE if the application supports tcp-wrapping or FALSE if not by reading the shared libraries used by this application.

Rename all files in lower case
rename is a really powerfull to, as its name suggests, rename files


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