Bash Scripting – String
Bash String is a data type similar to integer or boolean. It is generally used to represent text. It is a string of characters that may also contain numbers enclosed within double or single quotes.
Example: “geeksforgeeks”, “Geeks for Geeks” or “23690” are strings
Creating a String
A basic declaration and assignment of string
str1="GeeksforGeeks" str2=geeksforgeeks
The quotes can be omitted, but there shouldn’t be any space before and after the equals operator
Example
#!/bin/bash #Initializing the strings string1="GeekForGeeks" string2='Geeks for Geeks' string3=2345656778 #Printing the strings echo $string1 echo $string2 echo $string3
Output
Reading the string from the user
The input can be read from the user using the read command.
Example
#!/bin/bash echo What is your name read name echo "Hello there, $name"
Output
Concatenation of Strings
Strings in bash can be easily concatenated by listing the strings in order.
Example
#!/bin/bash
s1="Geeks"
s2="for"
s3="Geeks"
s4=${s1}${s2}${s3};
echo ${s4};
Output
Length of the String
The length of a given string can be accessed using the # operator by placing it inside the parameter expansion (curly braces) before the variable name.
Example
#!/bin/bash
string="geeksforgeeks"
echo "The length of the string is : ${#string}"
Output
String Replacement
Parts of an existing string can be replaced using / inside the parameter expansion. The syntax is given below.
${<variable_name>/<string_to_replace>/<new_string>}
This will replace the specified string with the new string once.
Example
string="Hello, Geeks!"
echo "String before replacement ${string}"
echo "String after replacement ${string/Geeks/World}"
Output
To replace every single matched string from the existing string, two slashes are used ‘//’ after the variable name, so it becomes.
${<variable_name>//<string_to_replace>/<new_string>}
Let us replace all the instances of the word butter from the below phrase.
Betty brought a bit of butter but the butter was bit of bitter so she brought some better butter to make the bitter butter better
#!/bin/bash
para=”Betty brought a bit of butter but the butter was bit of bitter so she brought some better butter to make the bitter butter better”
#This will replace every instance of butter in the phrase to BATTER
echo “${para//butter/BATTER}”
Output
