Sometimes, it requires checking whether a particular string exists in another string or not for programming purposes. Since there is no built-in function in Bash to do this task like other programming languages, there are some commands and operators in Bash to do this task. Different ways of checking if a string contains a substring in Bash are shown in this tutorial.

Different Examples of Checking Whether a String Contains a Substring or Not

The different ways of searching a substring in the main string using the “if” statement and “[[“ expression, and the different types of Bash commands are shown in this part of the tutorial.

Example 1: Search the String Using the “If” Statement

Create a Bash file with the following script that checks whether a string exists in another string or not using the “if-else” statement. Here, the values of the main string and substring are taken from the user using the read command. Next, the “if-else” statement checks the substring partially matches with any part of the

Output:

The following output appears after executing the previous script if the main string value is “Welcome to linuxhint” and the substring values are “linux” and “Ubuntu”:

Example 2: Search the String Using “[[”

Create a Bash file with the following script that checks whether a string exists in another string or not using the “[[” expression. Here, the values of the main string and substring are taken from the user using the read command like in the previous example. Next, the “[[” expression partially checks the substring matches with any part of the main string using “*”.

Output:

The following output appears after executing the previous script if the main string value is “Welcome to linuxhint” and the substring values are “come” and “Come”:

Example 3: Search the String Using the “Sed” Command

Create a Bash file with the following script that checks whether a string exists in another string or not using the “sed” command. Here, the value of the main string is taken from the user using the read command. The substring value is used in the regular expression of the “sed” command to check whether the substring exists inside the main string or not.

Output:

The following output appears after executing the previous script if the main string value is “Welcome to linuxhint” and the substring value is “Welcome”:

Example 4: Search the String Using the “Grep” Command

Create a Bash file with the following script that checks whether a string exists in another string or not using the “grep” command. Here, the values of the main string and substring are taken from the user using the read command like in the previous example. Next, the substring value is used with the “grep” command to check whether the value exists in the main string or not.

Output:

The following output appears after executing the previous script if the main string value is “Welcome to linuxhint” and the substring values are “come” and “go”:

Example 5: Search the String Using the “Awk” Command

Create a Bash file with the following script that checks whether a string exists in another string or not using the “awk” command. Here, the value of the main string is taken from the user using the read command. The substring value is used in the regular expression of the “awk” command to check whether the substring exists inside the main string or not.

Output:

The following output appears after executing the previous script if the main string value is “Welcome to linuxhint” and the substring value is “to”:

Example 6: Search the String Using the Case Operator

Create a Bash file with the following script that checks whether a string exists in another string or not using the “case” statement. Here, the values of the main string and substring are taken from the user using the read command like in the previous example. Next, the “case” statement partially checks the substring matches with any part of the main string using “*”.

Output:

The following output appears after executing the previous script if the main string value is “Welcome to linuxhint” and the substring values are “hint” and “Hint”:

Conclusion

The existence of the substring inside another string can be checked in different ways using a Bash script. The ways of using the different Bash commands and statements to do this task are shown in this tutorial.