How to use the command 'fold' (with examples)

The ‘fold’ command is used to fold long lines and break them into multiple lines of fixed width. It is particularly useful for displaying text on fixed-width output devices or for formatting text files.

Use case 1: Fold lines in a fixed width

Code:

fold --width <width> <path/to/file>

Motivation: This use case is useful when we have long lines in a file or input stream that need to be folded into multiple lines with a specific width. This makes the text more readable and suitable for displaying on fixed-width output devices.

Explanation:

• --width specifies the width of each folded line. Replace <width> with the desired width value.

Example output:

Suppose we have a file named ’example.txt’ with the following content:

This is a long line that needs to be folded into multiple lines with a fixed width.

Running the command:

fold --width 20 example.txt

The output will be:

This is a long line 
that needs to be
folded into multiple
lines with a fixed
width.

Use case 2: Count width in bytes

Code:

fold --bytes --width <width_in_bytes> <path/to/file>

Motivation: In certain scenarios, it may be required to calculate the width of each folded line in bytes instead of columns. This can be useful when dealing with specific character encodings or when precise byte counts are necessary.

Explanation:

• --bytes indicates that the width should be counted in bytes instead of columns.
• --width specifies the width of each folded line in bytes. Replace <width_in_bytes> with the desired byte width value.

Example output:

Suppose we have a file named ’example.txt’ containing non-ASCII characters:

This is a line with äöü characters.

Running the command:

fold --bytes --width 10 example.txt

The output will be:

This is a 
line with 
äöü char
acters.

Use case 3: Break line after the rightmost blank within the width limit

Code:

fold --spaces --width <width> <path/to/file>

Motivation: Sometimes, it is desirable to break the lines not just at a fixed width, but after the rightmost blank within the width limit. This can help maintain word boundaries and improve readability.

Explanation:

• --spaces specifies that the lines should be broken after the rightmost blank within the width limit.
• --width specifies the width of each folded line. Replace <width> with the desired width value.

Example output:

Suppose we have a file named ’example.txt’ with the following content:

This is a long line that needs to be folded into multiple lines with a fixed width.

Running the command:

fold --spaces --width 25 example.txt

The output will be:

This is a long line that
needs to be folded into
multiple lines with a
fixed width.

Conclusion:

The ‘fold’ command is a versatile tool that allows us to format and display long lines of text in a more readable manner. Whether we need to fold lines in a fixed width, count width in bytes, or break lines after the rightmost blank, the ‘fold’ command offers a wide range of options to suit various use cases.