Useful but Relatively Unknown Linux Commands

Commands can make our lives much easier. They do just one thing; but they excel at it. But there are literally thousands of them! Knowing which one to use in each particular situation demands a lot of our precious memory!

Here I'll keep a list of useful linux commands that I've recently learned, or that I use so seldom that I usually forget they exist. Most of them were taken from ;-).

Of course, suggestions are welcome!

Command Description
iostat -x -m 2 sda sdb show IO stats of disks /dev/sda and /dev/sdb
mongoose share current dir via HTTP
multitail MultiTail allows you to monitor logfiles and command output in multiple windows in a terminal, colorize, filter and merge
namei -om follow a pathname until a terminal point is found, showing owner, group and permissions
... | pv | ... watch progress of data through a shell pipeline
python -m SimpleHTTPServer share current dir via HTTP
cat file | ... | sponge file pipeline that reads from and writes to the same file
sed 'N;s/\n/ /' file join lines pairwise
ssh -N -L 1111:some.IP:3333 user@sshserver -p2222 SSH port forwarding:
swaks -t -s Deliver a standard test email to user AT on port 25 of
ts '[%Y-%m-%d %H:%M:%S]' adds a timestamp to the beginning of each line of input
vimdiff file1 file2 interactive, colored diff between 2 files