Scroll to navigation

GETINO(1) User Commands GETINO(1)

NAME

getino - print the unique inode number associated to a process file descriptor or namespace for a given PID

SYNOPSIS

getino [--pidfs|--cgroupns|--ipcns|--netns|--mntns|--pidns|--timens|--userns|--utsns] [--print-pid|-p] PID[:inode]...

getino [--print-pid|-p] PID[:inode]...

getino PID[:inode]...

DESCRIPTION

getino is a simple command that prints the inode numbers associated with the process file descriptor (pidfd) or namespace for all PIDs passed to it as arguments.

The kernel guarantees that the inode number associated with a process’s file descriptor is exempt from reuse during the current boot cycle; therefore, a process can be uniquely identified by its PID and the inode number, conveniently so with the format 'PID:inode'. As an example, this enables race-free signalling of processes with kill(1), which accepts the aforementioned PID format.

Inode numbers associated with a namespace for a given process are essentially namespace IDs, identical to the inode number reported by /proc/pid/ns/nstype, see namespaces(7) for more details.

OPTIONS

-p, --print-pid

Print both the PID and pidfd/namespace inode separated by a colon ':', in respective order. This format convention can be used to address processes in a race-free manner, e.g. for signalling with the kill(1) command.

--pidfs

Print the unique inode number for a process’s pidfs file descriptor.

--cgroupns

Print the unique cgroup namespace inode number. See cgroup_namespaces(7)

--ipcns

Print the unique ipc namespace inode number. See ipc_namespaces(7)

--netns

Print the unique network namespace inode number. See network_namespaces(7)

--mntns

Print the unique mount namespace inode number. See mount_namespaces(7)

--pidns

Print the unique pid namespace inode number. See pid_namespaces(7)

--timens

Print the unique time namespace inode number. See time_namespaces(7)

--userns

Print the unique user namespace inode number. See user_namespaces(7)

--utsns

Print the unique uts namespace inode number. See uts_namespaces(7)

-h, --help

Display help text and exit.

-V, --version

Display version and exit.

EXIT STATUS

getino has the following exit status values:

0

success

1

unspecified failure

NOTES

getino requires support for the pidfs pseudo-filesystem (introduced in Linux version 6.9), to retrieve a valid inode for a process file descriptor.

AUTHORS

Christian Goeschel Ndjomouo <cgoesc2@wgu.edu>

SEE ALSO

kill(1) pidfd_open(2) namespaces(7)

REPORTING BUGS

For bug reports, use the issue tracker <https://github.com/util-linux/util-linux/issues>.

AVAILABILITY

The getino command is part of the util-linux package which can be downloaded from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>.

2026-04-01 util-linux 2.42