String¶

Regular Expression Comparison¶

https://stackoverflow.com/questions/229551/how-to-check-if-a-string-contains-a-substring-in-bash

Bash Programming¶

1. case ... esac is different from switch(){} in C/C++. You do not have to return/exit manually after each branch.

not condition

if [ ! -d "$1" ]; then
fi

Shell Programing Trick¶

1. Generate 00, 01, ..., to 25.

    for i in {00..25}; do echo $i; done
   

   or

    seq -f %02g 0 25

Shell Scripting¶

export¶

A new child process forked from a parent process does not inherit parent's variables by default. The export command marks an environment variable to be exported with any newly forked child processes and thus it allows a child process to inherit all marked variables.

unset¶

References¶

https://stackoverflow.com/questions/6877727/how-do-i-delete-an-exported-environment-variable

Parse Arguments in Bash¶

Environment Variables¶

export

unset

Tips and Traps¶

1. explainshell.com is a great place for learning shell.

2. Bash-it/bash-it is a great community driven Bash framework.

3. It is suggested that you avoid writing complicated Bash scripts. IPython is a much better alternative.

4. Do NOT use ; to delimit paths passed to a shell command because ;