.TH "CAPNG_SET_ROOTID" "3" "March 2026" "Red Hat" "Libcap-ng API"
.SH NAME
capng_set_rootid \- set namespace root id
.SH "SYNOPSIS"
.B #include <cap-ng.h>
.sp
int capng_set_rootid(uid_t rootid);

.SH "DESCRIPTION"

capng_set_rootid sets the root user ID for file capabilities operations. The
value is host-endian and relative to the caller's user namespace. Pass
CAPNG_UNSET_ROOTID to clear a previously selected namespace root ID and go
back to writing regular V2 file capabilities. Other values select V3 file
capabilities; the kernel validates and maps the user ID when the capabilities
are written.

.SH "RETURN VALUE"

On success, it returns 0. It returns -1 if there is an internal error or the
kernel headers used to build the library do not support V3 file capabilities.

.SH "SEE ALSO"

.BR capng_apply_caps_fd (3),
.BR capabilities (7)

.SH AUTHOR
Steve Grubb