FileTest#writable?

(::path file_name) -> bool

File.writable?(file_name) → true or false

static VALUE
rb_file_writable_p(VALUE obj, VALUE fname)
{
    return RBOOL(rb_eaccess(fname, W_OK) >= 0);
}

Returns true if the named file is writable by the effective user and group id of this process. See eaccess(3).

Note that some OS-level security features may cause this to return true even though the file is not writable by the effective user/group.

See also #world_writable? #writable_real? #world_readable? #zero? also in 4.1 · 4.0 · 3.3 · 3.2 · 3.1 · 3.0