setUnixUser
Tries to set the UNIX user identifier on @credentials. This method is only available on UNIX platforms.
This operation can fail if #GCredentials is not supported on the OS or if the native credentials type does not contain information about the UNIX user. It can also fail if the OS does not allow the use of "spoofed" credentials.
Return
true if @uid was set, false if error is set.
Since
2.26
Parameters
uid
The UNIX user identifier to set.