luser is a drop-in replacement for os/user which allows you to lookup users
and groups in cross-compiled builds without cgo.
os/user requires cgo to lookup users using the target OS's API. This is
the most reliable way to look up user and group information. However,
cross-compiling means that os/user will only work for the OS you're using.
user.Current() is usable when building without cgo, but doesn't always
work. The $USER and $HOME variables could be different from what you
expect or not even exist.
If you want to cross-compile a relatively simple program that needs to write a config file somewhere in the user's directory, the last thing you want to do is figure out some elaborate build scheme involving virtual machines.
luser has the same API as os/user. You should be able to just replace
user. with luser. in your files and let goimports do the rest. The
returned *User and *Group types will have an IsLuser field indicating
whether or not a fallback method was used.
Install the package with:
$ go get github.com/tweekmonster/luserA sample program called luser can be installed if you want to see the
fallback results on your platform:
$ CGO_ENABLED=0 go install github.com/tweekmonster/luser/cmd/luser
$ luser -c
$ luser username
$ luser 1000os/user functions are used when built with cgo. Otherwise, it falls back
to one of the following lookup methods:
| Method | Used for |
|---|---|
/etc/passwd |
Parsed to lookup user information. (Unix, Linux) |
/etc/group |
Parsed to lookup group information. (Unix, Linux) |
getent |
Optional. Find user/group information. (Unix, Linux) |
dscacheutil |
Lookup user/group information via Directory Services. (Darwin) |
id |
Finding a user's groups when using GroupIds(). |
Note: Windows should always work regardless of the build platform since it
uses syscall instead of cgo.
luser.Userandluser.Groupare new types. The underlyinguser.*types are embedded, however (e.g.u.User).- The lookup methods use
exec.Command()and will be noticeably slower if you're looking up users and groups a lot. - Group-releated functions will only be available when compiling with Go 1.7+.