10 Useful Linux Commands

Here's a list of 10 commands which may come handy when using the command line in Linux:

Search for all files modified in the last N days containing a specific text in their name

find DIR -mtime -N -name "*TEXT*"

For example:

find ~ -mtime -5 -name "*log*"

Will display all the files modified in the past 5 days which include the text 'log' in their filename.

Determine which processes use the most memory

ps aux | sort -nk 4 | tail

Will show the first 10 processes which use the most memory, using ascendant sorting. Alternately:

ps aux | sort -nrk 4 | head

Will show the first 10 processes using most memory, using descendent sorting.

Output of ps aux | sort -nrk 4 | head

Display the username which is currently logged in

whoami

Show date using format modifiers

date +"%H:%M:%S"

Will output time in format HOUR:MINUTE:SECOND. You can use any format specifiers explained in the man page. The double quotes are required in case you need to use spaces.

Showing date in format month, day year

Show info about a specific user

finger $USER

Output of finger $USER

Show disk usage separately for each partition

df -h

The -h switch will tell df to show human-readable sizes (KB, MB and GB when it is the case)

df -B 1K

Will show sizes in kilobytes.

Show which modules are loaded

lsmod

Add or remove a module to/from the Linux kernel

Insert a module:

modprobe MODULE

Remove a module:

modprobe -r MODULE

Search for a file using locate

locate FILENAME

Will search the locate database (created with updatedb) for any path or file which contains FILENAME.

Change the encoding of a text file

iconv -f INITIAL_ENCODING -t DESIRED_ENCODING filename

For example:

iconv -f ISO-8859-16 -t UTF-8 myfile.txt

Will change the encoding of myfile.txt from ISO-8859-16 (Romanian) to UTF-8.