github.com/containers/podman/v5@v5.1.0-rc1/docs/source/markdown/options/userns-uid-map-user.md (about)

     1  ####> This option file is used in:
     2  ####>   podman build, farm build
     3  ####> If file is edited, make sure the changes
     4  ####> are applicable to all of those.
     5  #### **--userns-uid-map-user**=*user*
     6  
     7  Specifies that a UID mapping to be used to set ownership, at the
     8  filesystem level, on the working container's contents, can be found in entries in the `/etc/subuid` file which correspond to the specified user.
     9  Commands run when handling `RUN` instructions defaults to being run in
    10  their own user namespaces, configured using the UID and GID maps.
    11  If --userns-gid-map-group is specified, but --userns-uid-map-user is not specified, `podman` assumes that the specified group name is also a
    12  suitable user name to use as the default setting for this option.
    13  
    14  **NOTE:** When this option is specified by a rootless user, the specified mappings are relative to the rootless user namespace in the container, rather than being relative to the host as it is when run rootful.