Do you want to know the size of a directory in Linux? Use the du command.

du -sh

Explanation

The du command estimates the space used by a directory.

The options -sh are (from man du):

  -s, --summarize
         display only a total for each argument

  -h, --human-readable
         print sizes in human readable format (e.g., 1K 234M 2G)

To check more than one directory and get the total size of those directories, use

du -sch *

What does the extra option mean?

  -c, --total
         produce a grand total

Include hidden files?

du -sch * .*

Want to know how much disk space has been used?

du -h .

I have been irritated not having standard keyboard shortcuts, like Ctrl-arrow left (move word left) and Ctrl-arrow right (move word right), available on the bash command line. It turns out they are. If you know what the meta key is. Meta key? Yes, I didn’t know which key this was either.

It turns out that it is the Alt key. This is because historically, many Unix workstations had a key labeled Meta where PCs have a key labeled Alt.

So here is a little bash command line cheat sheet.

• Ctrl-a: Move to the start of the current line.
• Ctrl-e: Move to the end of the line.
• Ctrl-f: Move forward a character.
• Ctrl-b: Move back a character.
• Meta-f: Move forward to the end of the next word. Words are composed of letters and digits.
• Meta-b: Move backward to the start of the next word. Words are composed of letters and digits.

Have fun.

I needed to find out which files a process was using. I used the following commands to do this.

The ps command to get the process id (PID) of the process.

$ ps -aef | grep

Then the lsof command to list the files being used by the process.

$ lsof -p

If you want to count the files being used, use the following command.

$ lsof -p  | wc -l

Have fun.

Grrrrrrr ran into my inotify problem again. So I was wondering how I can see which program has files opened and how many. Well as with everything under Linux it is possible with a few “simple” commands. Try the following command for fun and entertainment.

$ lsof | awk ‘{print $1}’ | sort | uniq -c | sort -g -k 1 | tail

• lsof: lists the open files
• awk: takes the first column of the output
• sort: yep it sorts the output
• uniq: counts all the same value
• sort: do you want me to repeat it? a little clarification is necessary -k tells which column to sort on and -g makes sure that the contents is treated like a number
• tail: gives the last ten entries