Commands by Gomex (2)

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Shows space used by each directory of the root filesystem excluding mountpoints/external filesystems (and sort the output)
Excludes other mountpoints with acavagni's "mountpoint" idea, but with -exec instead of piping to an xargs subshell. Then, calling "du" only once with -exec's "+" option. The first "\! -exec" acts as a test so only those who match are passed to the second "-exec" for du.

generate a telephone keypad
Draw a telephone keyboard, using just a shell built-in command.

Big (four-byte) $RANDOM
Sometimes, in a shell script, you need a random number bigger than the range of $RANDOM. This will print a random number made of four hex values extracted from /dev/urandom.

Get all IPs via ifconfig
The initial version of this command also outputted extra empty lines, so it went like this: 192.168.166.48 127.0.0.1 This happened on Ubuntu, i haven't tested on anything else.

show the difference

Rename files in batch

sniff network traffic on a given interface and displays the IP addresses of the machines communicating with the current host (one IP per line)

Find all the files more than 10MB, sort in descending order of size and record the output of filenames and size in a text file.
This command specifies the size in Kilobytes using 'k' in the -size +(N)k option. The plus sign says greater than. -exec [cmd] {} \; invokes ls -l command on each file and awk strips off the values of the 5th (size) and the 9th (filename) column from the ls -l output to display. Sort is done in reversed order (descending) numerically using sort -rn options. A cron job could be run to execute a script like this and alert the users if a dir has files exceeding certain size, and provide file details as well.

dont execute command just add it to history as a comment, handy if your command is not "complete" yet

Show IP Address in prompt --> PS1 var
when working with many machines in a computer lab need to know the IP addr is very large, this is a simplistic solution to make things easier


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