Single-Quotes

When shell encounters a single-quote ('), it starts creating a string using these rules:

1. Another single-quote ends the contents and cannot be escapaed (see below rule)

2. Escape sequences are not expanded (e.g., \t is not translated into a literal TAB)

3. Variables are not expanded (e.g., $foo remains $foo)

4. Command substitutions are not performed (e.g., $(date) and `date` remain unchanged)

For example:

1 #!/bin/sh
2 echo '$bird $(is) `\t\h\e` ${word}'

Produces:

$bird $(is) `\t\h\e` ${word}