Provided by: uidmap_4.2-3.1ubuntu5_amd64
newgidmap - set the gid mapping of a user namespace
newgidmap pid gid lowergid count [pid gid lowergid count [ ... ]]
The newgidmap sets /proc/[pid]/gid_map based on it's command line arguments and the gids allowed in /etc/subgid. After the pid argument, newgidmap expects sets of 3 integers: gid Begining of the range of GIDs inside the user namespace. lowergid Begining of the range of GIDs outside the user namespace. count Length of the ranges (both inside and outside the user namespace). newgidmap verifies that the caller is the owner of the process indicated by pid and that for each of the above sets, each of the GIDs in the range [lowergid, lowergid+count] is allowed to the caller according to /etc/subgid before setting /proc/[pid]/gid_map. Note that newgidmap may be used only once for a given process.
There currently are no options to the newgidmap command.
/etc/subgid List of users subordinate group IDs. /proc/[pid]/gid_map Mapping of gids from one between user namespaces.