Format a file and display the result to the console
Format a file, overwriting the original file in-place
Format a file, and then simplify the code, overwriting the original file
Print all (including spurious) errors
gofmt [flags] [ path ... ]
Without an explicit path, it processes the standard input. Given a file, it operates on that file; given a directory, it operates on all .go files in that directory, recursively. (Files starting with a period are ignored.) By default, gofmt prints the reformatted sources to standard output.
Do not print reformatted sources to standard output. If a file's formatting is different than gofmt's, print diffs to standard output.
Print all (including spurious) errors.
Do not print reformatted sources to standard output. If a file's formatting is different from gofmt's, print its name to standard output.
- -r rule
Apply the rewrite rule to the source before reformatting.
Try to simplify code (after applying the rewrite rule, if any).
Do not print reformatted sources to standard output. If a file's formatting is different from gofmt's, overwrite it with gofmt's version.
Formatting control flags:
Print comments; if false, all comments are elided from the output.
Indent with tabs; if false, spaces are used instead.
Tab width in spaces.
The rewrite rule specified with the -r flag must be a string of the form:
pattern -> replacement
Both pattern and replacement must be valid Go expressions. In the pattern, single-character lowercase identifiers serve as wildcards matching arbitrary sub-expressions; those expressions will be substituted for the same identifiers in the replacement.
When gofmt reads from standard input, it accepts either a full Go program or a program fragment. A program fragment must be a syntactically valid declaration list, statement list, or expression. When formatting such a fragment, gofmt preserves leading indentation as well as leading and trailing spaces, so that individual sections of a Go program can be formatted by piping them through gofmt.
To check files for unnecessary parentheses:
gofmt -r '(a) -> a' -l *.go
To remove the parentheses:
gofmt -r '(a) -> a' -w *.go
To convert the package tree from explicit slice upper bounds to implicit ones:
gofmt -r 'α[β:len(α)] -> α[β:]' -w $GOROOT/src/pkg
The implementation of -r is a bit slow.
This manual page was written by Michael Stapelberg <email@example.com>, for the Debian project (and may be used by others).