]> Eric Biederman Creation, 2013 newuidmap 1 User Commands shadow-utils &SHADOW_UTILS_VERSION; newuidmap set the uid mapping of a user namespace newuidmap pid uid loweruid count uid loweruid count ... The newuidmap sets /proc/[pid]/uid_map based on its command line arguments and the uids allowed. The subid delegation can come either from files (/etc/subuid) or from the configured NSS subid module. Only one of them can be chosen at a time. So, for example, if the subid source is configured as NSS and useradd is executed, then the command will fail and the entry will not be created in /etc/subuid. Note that the root user is not exempted from the requirement for a valid /etc/subuid entry. After the pid argument, newuidmap expects sets of 3 integers: uid Beginning of the range of UIDs inside the user namespace. loweruid Beginning of the range of UIDs outside the user namespace. count Length of the ranges (both inside and outside the user namespace). newuidmap verifies that the caller is the owner of the process indicated by pid and that for each of the above sets, each of the UIDs in the range [loweruid, loweruid+count) is allowed to the caller according to /etc/subuid before setting /proc/[pid]/uid_map. Note that newuidmap may be used only once for a given process. There currently are no options to the newuidmap command. /etc/subuid List of user's subordinate user IDs. /proc/[pid]/uid_map Mapping of uids from one between user namespaces. login.defs5 , newusers8 , subuid5 , useradd8 , usermod8 , userdel8 .