gofmt (1) - Linux Man Pages
gofmt: formats Go programs
gofmt - formats Go programs
SYNOPSISgofmt [flags] [ path ... ]
DESCRIPTIONWithout 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.
EXAMPLESTo 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
BUGSThe implementation of -r is a bit slow.
This manual page was written by Michael Stapelberg <stapelberg [at] debian.org>, for the Debian project (and may be used by others).