Shell in nutshell or little tips and tricks

Today I will try to show  some tricks in UNIX/Linux shells maybe you do not know:

- use . (dot) to execute command or script in the current instance of the shell, this help much when you try to set some variables or change to directory with long and complicated path

- use - (dash) to go to previous working directory. this do not work in bourne shell

- use ${n..nn} in bash to generate sequence of numbers. Maybe was something similar in korn shell, but I can't remember.

$ printf "%03d " {1..100}

Also you can use seq program (mainly available in Linux)

$ printf "%03d " `seq 1 100`

- use bc to make arithmetic calculations on the fly:

# echo 2^15|bc

32768

- printf is very helpfull when you try to create well formatted output. Just follow the same format as in C

To be continued (maybe)...