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Bash Split String

In this topic, we have defined how to split a string in bash shell scripting.

In some cases, we might need to split the string data to perform some specific tasks. Most of the programming languages contain built-in function 'split' to divide any string data into multiple parts. However, bash does not contain such type of built-in function. But we can use delimiters to split any string data in bash scripting. The delimiter can be either a single character or a string with multiple characters.

Check out the methods below to understand how to split string in a bash shell:

Split using $IFS variable

Following are the steps to split a string in bash using $IFS:

  • $IFS is a special internal variable which is used to split a string into words. $IFS variable is called 'Internal Field Separator' which determines how Bash recognizes boundaries. $IFS is used to assign the specific delimiter [ IFS='' ] for dividing the string. The white space is a default value of $IFS. However, we can also use values such as '\t', '\n', '-' etc. as the delimiter.
  • After assigning the delimiter, a string can be read by two options: '-r' and '-a'. i.e., read -ra ARR <<< "$str".
    Here, the option '-r' is used to define that backslash (\) is a character rather than escape character. The '-a' option is used to define that the words (separated by $IFS) are assigned to the sequential index of array beginning at zero.
  • Then we apply bash 'for' loop to access the tokens which are split into an array.

Let's understand this mechanism with the help of some examples:

Example 1: Bash Split String by Space

In this example, a string is split using a space character delimiter.

Bash Script

Output

If we input a string "We welcome you on Javatpoint", the output will look like this:

Bash Split String

Example 2: Bash Split String by Symbol

In some cases, we may have a requirement to split a string by other delimiters such as a symbol or specific character. In this example, a string is split using a comma (,) symbol character as a delimiter.

Bash Script

Output

Bash Split String

Split without $IFS variable

In bash, a string can also be divided without using $IFS variable. The 'readarray' command with -d option is used to split the string data. The -d option is applied to define the separator character in the command like $IFS. Moreover, the bash loop is used to print the string in split form.

Let's understand this logic with the help of some example:

Example 1: Bash Split String by Symbol

This example defines how a string value can be split without using $IFS. As per the script, a text value should be entered with the colon (:) sign so that it can be split. Check out the bash script below:

Bash Script

Output

Bash Split String

Example 2: Bash Split String by another string

In this example, we have used idiomatic expressions where parameter expansion has completed.

Bash Script

In this bash script, we have used the following Parameter- Expansions:

  • ${parameter%%word}
    It removes the longest matching suffix pattern.
  • ${parameter#word}
    It removes the shortest matching prefix pattern.

Output

Bash Split String

Example 3: Bash Split String using Trim Command

In this example, we have used trim (tr) command to split a string. Instead of using the read command, the trim command is used to split a string on the delimiter.

Bash Script

Output

Bash Split String

Note: It should be noted that array elements are divided on 'space delimiter' if we apply a trim command to split a string. For example, elements like 'Windows OS' will be treated as two different words.

Conclusion

In this topic, we demonstrated how to split a string in bash scripting with different types of scenarios with or without using delimiter.


Next TopicBash Substring




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