bash script

Bash Script

• Bash is a Unix shell written by Brian Fox for the GNU Project as a free software replacement for the Bourne shell .• Released in 1989,it has been distributed widely as the

shell for the GNU operating system and as a default shell on Linux and Mac OS X.

Let’s explore Bash Script…

1.Variables

Global vs. Local variables

2.Conditional statements and loops

A.Conditional statements

If/else

Elif

Arithmetic Comparisons

Case

b.Loops

While

For(with numbers)

For(with directories)

For(with arrays)

Until

3.Bash functions

Syntax to create a bash function:

Function with arguments

Functions with returned values

4.String manipulations

a.String length

b.Substring extraction

c.Shortest Substring Match

d.Find and Replace String Values

e.Replace all the matches

f.Replace beginning and end

f.Replace beginning and end

5.I/O Redirection

a.Standard Output “>”

a.Standard Output “>”

b.Standard Input “<“

b.Standard Input “<“

c.Pipes “|”

6.Special commands

a.Grep

• Is used to search a characters chain within a file• -v displays the lines that do not contain the string• -c count the number of lines containing the string• -n each line containing the string is numbered• -x the line that exactly matches the string• -l displays the names of files that contain the string

b.Find

• Is used to fined files based on specific criteria.• Syntax: find <folder> <search criteria>

• -name search by name• -perm search by access rihghts on file,• -user search by file’s owner,• -group search by file’s group,

c.Awk

• Is used to print specific lines and columns from a file, with conditions.• Syntax : awk '{print $NF}' file

d.Sed

• The SED UNIX Command in Linux enables you to work with the text inside your files and can be used to perform different functions to it.• Syntax :

e.Alias

• Is used to enable a replacement of a command by another string• Syntax : alias myalias=“command_name”

Thank you for your attention