How to get username?

General Usage
6

Something like:

struct uv_passwd
    username::Cstring
    uid::Clong
    gid::Clong
    shell::Cstring
    homedir::Cstring
end

function username()
    for varname in ("LOGNAME", "USER", "LNAME",  "USERNAME")
        username = get(ENV, varname, "")
        !isempty(username) && return username
    end
    p = Ref{uv_passwd}()
    ret = @ccall uv_os_get_passwd(p::Ref{uv_passwd})::Cint
    Base.uv_error("get_passwd", ret)
    username = unsafe_string(p[].username)
    @ccall uv_os_free_passwd(p::Ref{uv_passwd})::Cvoid
    return username
end

Note also that you should check whether the environment variables are non-empty, not just whether they exist. This is what Python does.

Update: Alternatively, Julia’s Libc module apparently already contains an undocumented function for this, though it doesn’t check the environment variables first:

julia> Libc.getpwuid(Libc.getuid(), true)
Base.Libc.Passwd("stevenj", 0x00000000000001f5, 0x0000000000000014, "/bin/zsh", "/Users/stevenj", "Steven G. Johnson")

julia> Libc.getpwuid(Libc.getuid(), true).username
"stevenj"

I filed an issue: username() function (analogous to homedir()) · Issue #48302 · JuliaLang/julia · GitHub

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