Download - Shell Scripting in Linux
Shell ScriptingLinux shell programming
04/12/23
Introduction • A shell is a program constructed of shell commands
( $shell,$path,Ls,pwd,mkdir..)• Shell is an environment for user interaction.But it is
not a part of kernel.• Shell is just like as BAT files in MS-DOS.• By default,Bash shell is default shell for Linux.
04/12/23
Features of Shells• Shells are CASE SENSITIVE.• Shells allows interaction with kernel.• Shells allow one to create functions and pass
arguments to them.• Shells provide help for each and every command
using man or help.• Helps in automation of tasks and thus time saving
04/12/23
Types of shells• Following types of shells are available in linux:
Some other types of shells available are KSH Korn shell,TCSH tenex/Tops C shell
Shell Name Developer Prompt
Description
Bash – Bourne again
Brian Fox &Chet Ramey
$ Bash is the replacement of sh shell.It provides many tools for editing and manipulating history.
CSH - C shell Bill Joy % C shell has its syntax much same as that of C language.
04/12/23
Shell Scripting• A script is defined as just a plain text file or ASCII
file – with a set of linux / unix commands.– Flow of control– I\O facilities
• A shell script can be created using any
text editor like vim,emac,notepad++ etc.
04/12/23
• Shell script allow use of variables.• Shell scripts are interpreted directly and are not
compiled as c\c++ codes.• Shells provide many features including loop
constructs,arrays,variables,branches and functions.• shells provide logic with other utilities like
pipelining,redirection etc.• Shells allow file and directory management features.
04/12/23
Example of Shell scripting
04/12/23
Structure of a script• #!/bin/bash –it defines that in which shell will be used
to run the script.• # comments –comments can be made by using #
symbol in a script.• Chmod +x script.sh – to tell the linux that file is
executable.• ./script.sh to execute the script.
To check current shell ,type following:
echo $SHELL.
04/12/23
Advantages of shell scripting• Shell script is much quicker
than programming in any
other languages.
• To automate the frequently
performed tasks.
• Easy to use and understand.
Non-geeks can also modify
scripts.04/12/23
Disadvantages of shell scripting
• Slow execution speed.
• Prone to costly errors.
• Compatability problems
04/12/23
ReferencesShell Scripting for Unix/Linux: Shell scripting
advantages and disadvantages Bash Shell Script Function Examples Linux Shell Scripting Tutorial - A Beginner's
handbook LinuxHelp.net
04/12/23
04/12/23