Access with more than 16 Unix groups
This article tells you how to access the file-system when you have permission to access more than 16 Unix groups.
Unix groups are used to manage access to resources on the file-system. You can find out the group ownership of a file or directory using the "ls -l" command, for example:
$ ls -l test.txt -rw-r--r-- 1 jbloggs open 3 Nov 22 11:59 test.txt
$ groups users gws_ukca esacat1 ecmwf ukmo open
As you request access to more datasets, group workspaces and other resources on JASMIN the number of Unix groups associated with your user will increase. A user can be granted access to any number of Unix groups.
The 16-group session limit
However, on a standard Unix file-system (and on JASMIN) a user has a hard limit of 16 groups that are accessible within a given session. This means that sometimes you may be refused permission to read/write to a given directory even though your user does have the required permission.
Using "newgrp" to overcome the 16-group limit
$ newgrp ecmwf