Bash Scripting

String Manipulations

• To replace all substrings by another, use the following syntax:

echo ${stringZ//abc/xyz}

This would replace all occurences of abc in stringZ by xyz. The following replaces only the first match:

echo ${stringZ/abc/xyz}

Special Symbols

• "$@" expands to all command-line parameters.
• "\n" in a variable does not necessarily works as expected. Eg, no newline is created.
• \ before a newline actually escapes the newline. Thus, you can create multi-line strings or commands just by terminating a line with the \ symbol.

Tests

• -n checks if a string is not empty, -z if it is empty.
• [ is not a keyword but a command (a program!). It is recommended to use [[ in tests which is a keyword.

Standard Input / Output

• "<<<" can be used to feed a string as standard input.

Command Line Utilities

• sdiff -s will generate a formatted output of the differences between two files. Very useful.