spell

Classic Unix spell-checking utility

TLDR

Check spelling in a file

$ spell [file.txt]

Check spelling from stdin

$ echo "[text to check]" | spell

Check using British spelling rules

$ spell -b [file.txt]

Use a custom word list as additional dictionary

$ spell +[custom_words.txt] [file.txt]

Show all words not in dictionary including plausible derivations

$ spell -v [file.txt]

Use a specific dictionary file

$ spell -d [path/to/dictionary] [file.txt]

Check multiple files

$ spell [file1.txt] [file2.txt]

SYNOPSIS

spell [options] [+localfile] [file_...]

spell is a classic Unix spell-checking utility that reports misspelled words. It reads text from files (or stdin if none specified), looks up each word in its dictionary, and outputs words that are not found or cannot be derived from known words.Unlike modern spell checkers such as aspell or ispell, spell does not suggest corrections or offer an interactive interface. It simply lists unrecognized words to standard output, making it suitable for scripting and batch processing.The -v option shows words that are derivable but not literally in the dictionary. A custom word list can be specified with +filename to supplement the system dictionary with domain-specific or technical terms.On most modern Linux distributions, the spell command is provided by GNU spell, which is a wrapper around ispell. The traditional Unix spell had additional options (-x for stem printing) that are ignored in the GNU version for compatibility.

PARAMETERS

-b, --british

Use British spelling rules (colour, centre, -ise endings)

-v, --verbose

Print all words not literally in the dictionary, including plausible derivations

-d, --dictionary=FILE

Use FILE as the dictionary to look up words

-i, --ispell=PROGRAM

Call PROGRAM as Ispell (default: ispell)

-n, --number

Print line numbers before each line

-o, --print-file-name

Print file names before each line

-l, --all-chains

Follow chains of included files (kept for compatibility)

+localfile_

Use additional word list; words found here are not reported as misspellings

-h, --help

Print a summary of options

-V, --version

Print version number

CAVEATS

spell provides no spelling suggestions and no interactive correction. It may flag proper nouns, technical terms, and abbreviations as misspellings. The dictionary coverage varies by distribution. For more sophisticated spell checking, consider aspell or ispell.

HISTORY

spell was developed by Stephen C. Johnson at Bell Labs and first appeared in Version 6 Unix in 1975. It was one of the earliest text-processing utilities and helped establish Unix as a document preparation system. The command has remained largely unchanged, preserving its simple, filter-based design philosophy.