Bash

Script

$ type script
$ chmod +x script
$ ./script
$ .script
$ source script
$ bash script

#!/bin/bash

Command Line

Everything is a file
255 Byte
The maximum length for a file name is 255 bytes.
The maximum combined length of both the file name and path name is 4096 bytes.
This length matches the PATH_MAX that is supported by the operating system.
Names are case-sensitive

Special chars to avoid in names/filenames

/   Never
\   Escaped
-   Never at beginning
[]  Escaped
{}  Escaped
*   Escaped
'   Escaped
"   Escaped

Wildcards

*  asterisk        | any char
?  question mark   | single char
[] square brackets | set of single char or a range of chars

List files and folders

$ ls
$ ls folder
$ ls ./folder
$ ls /path/folder
$ ls ~/folder
$ ls ~/folder/*.jpg
$ ls ~/folder/*txt*
$ ls -R folder (list of subfolders)

$ ls -l (single column)
 - regular file
 _ executable
 d directory
 l symbolic link
 s socket
 b block device
 c character device
 p named pipe

$ ls -m (comma-separated list)
$ ls -a (hidden files and folders)

$ ls -F (file type)
Symbols and file types
 * Executable
 / Directory
 @ Symbolic link
 | FIFO
 = Socket

$ ls --color (content in color)
$ dircolors
$ dircolors --print-database
$ ls -F --color
$ la -la
$ ls -r
$ ls -X (sort by extension)
$ ls -t (sort by date)
$ ls -S (sort by content)
$ ls -h
$ ls -laS
$ ls -h