FMT(1) General Commands Manual FMT(1)

fmt - Reformat paragraphs from input (or standard input) to stdout.

[OPTION]... [FILE]...

Reformat paragraphs from input (or standard input) to stdout.

First and second line of paragraph may have different indentations, in which case the first line's indentation is preserved, and each subsequent line's indentation matches the second line.
Like -c, except that the first and second line of a paragraph *must* have different indentation or they are treated as separate paragraphs.
Attempt to detect and preserve mail headers in the input. Be careful when combining this flag with -p.
Split lines only, do not reflow.
Insert exactly one space between words, and two between sentences. Sentence breaks in the input are detected as [?!.] followed by two spaces or a newline; other punctuation is not interpreted as a sentence break.
Reformat only lines beginning with PREFIX, reattaching PREFIX to reformatted lines. Unless -x is specified, leading whitespace will be ignored when matching PREFIX.
Do not reformat lines beginning with PSKIP. Unless -X is specified, leading whitespace will be ignored when matching PSKIP
PREFIX must match at the beginning of the line with no preceding whitespace.
PSKIP must match at the beginning of the line with no preceding whitespace.
Fill output lines up to a maximum of WIDTH columns, default 75. This can be specified as a negative number in the first argument.
Goal width, default of 93% of WIDTH. Must be less than or equal to WIDTH.
Break lines more quickly at the expense of a potentially more ragged appearance.
Treat tabs as TABWIDTH spaces for determining line length, default 8. Note that this is used only for calculating line lengths; tabs are preserved in the output.
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v(uutils coreutils) 0.11.0

2026-09-01