fold - macOS

Overview

The fold command in macOS is used to wrap each input line to fit a specified width. Its primary purpose is to ensure that long lines of text fit within a certain width, making the content suitable for display in environments with limited horizontal space, such as terminal windows or printed documents. This command is most effectively used in text processing scripts and pipelines where format and readability are key.

Syntax

The basic syntax of the fold command is:

fold [options] [files...]

If no files are specified, fold reads from the standard input.

Parameters:

• [files…]: One or more files to be processed. If no files are provided, fold processes the standard input.

Options/Flags

• -b, –bytes: Count width in bytes rather than column positions. This is useful for processing non-ASCII characters where a character may span multiple bytes.
• -s, –spaces: Break at spaces. Use this flag to ensure that lines break at space characters for a cleaner look, rather than breaking words across lines.
• -w, –width=WIDTH: Specify the desired width at which the lines should be folded. The default value is 80 columns.

Examples

Example 1: Basic Folding

Fold text to the default width (80 columns):

echo "This is a very long line of text that needs to be folded because it doesn't fit in a standard terminal window." | fold

Example 2: Custom Width

Fold text at 40 columns:

echo "This is a very long line of text that needs to be folded because it doesn't fit in a standard terminal window." | fold -w 40

Example 3: Fold at Spaces

Fold text at spaces to avoid breaking words:

echo "This is a very long line of text that needs to be folded because it doesn't fit in a standard terminal window." | fold -s -w 40

Common Issues

• Broken Words: By default, fold may split words across lines. Use the -s option to avoid this.
• Non-ASCII Characters: When dealing with non-ASCII text, column widths may not align correctly if not using the -b option.

Integration

fold can be effectively combined with other text processing tools like grep, awk, or sed in scripts:

cat report.txt | fold -w 50 | grep 'keyword'

This chain folds the text to 50 columns, then filters lines containing ‘keyword’.

Related Commands

• cut: Remove sections from each line of files.
• fmt: Reformat paragraph text.
• tr: Translate or delete characters.

For detailed documentation and more examples, you can refer to the fold man page by executing man fold in the terminal.