Essential Shell Scripting Commands

Shell Scripts

Shell scripts allow users and administrators to automate tasks using a scripting language like Bash or PowerShell.

essential for automation
good for:
- creating backups
- automating software updates
- installing software
- automating system maintenance
Analysts can use shell scripts to
- locate important information stored in logs
- automate complicated commands

Shell Command Processor Types

Shell	Name	Description
ksh	Korn Shell	Typically used on proprietary UNIX systems, such as IBM’s AIX.
sh	Bourne Shell	A simple, lightweight shell found on most *nix systems and devices.
csh	C Shell	Often associated with proprietary UNIX, such as Oracle’s Solaris.
tcsh	C Shell	An improved version of C Shell, available for many platforms.
bash	Bourne Again Shell	An improved version of sh and very widely used.
zsh	Z Shell	Expands upon Bash shell and supports many plugins to expand its functionality.

Common Shell Commands

Command	Description
`cat`	Display the content of a file.
`tail`	Display the last 10 lines of a file.
`head`	Display the first 10 lines of a file.
`touch`	Create an empty file.
`mkdir`	Create a directory.
`cp`	Copy a file (or directory).
`mv`	Move an object, such as a file. Also used to rename files and directories.
`rm`	Remove a file or directory.
`file`	Determine the type of a file.
`ls`	Display the contents of a directory.
`locate`	Search for files. Locate uses a database to improve speed and efficiency of searches.
`find`	Search for files by parsing the file system.
`wget`	Simple command to retrieve content from an HTTP server.
`curl`	Similar to wget but includes more sophisticated options.

Administrative Shell Commands

Command	Description
`vi`/`vim`	A file editor for use in a terminal. Very popular but nonintuitive to use.
`su`	Substitute or switch user.
`sudo`	Precedes a command that requires elevated privileges.
`useradd`	Create a user account.
`usermod`	Change the attributes of a user account.
`chmod`	Determines who is allowed to make what changes to a particular file or folder.
`chown`	Determines who owns a particular file or folder.
`mkfifo`	Similar in concept to a standard \| style pipe but implemented as an actual file.