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PROTECT(1) FreeBSD General Commands Manual PROTECT(1)
NAME protect - protect processes from being killed when swap space is exhausted
SYNOPSIS protect [-i] command protect [-cdi] -g pgrp protect [-cdi] -p pid
DESCRIPTION The protect command is used to mark processes as protected. The kernel does not kill protected processes when swap space is exhausted. Note that this protected state is not inherited by child processes by default.
The options are:
-c Remove protection from the specified processes.
-d Apply the operation to all current children of the specified processes.
-i Apply the operation to all future children of the specified processes.
-g pgrp Apply the operation to all processes in the specified process group.
-p pid Apply the operation to the specified process.
command Execute command as a protected process.
Note that only one of the -p or -g flags may be specified when adjusting the state of existing processes.
Daemons can be protected on startup using <name>_oomprotect option from rc.conf(5).
EXIT STATUS The protect utility exits 0 on success, and >0 if an error occurs.
EXAMPLES Mark the Xorg server as protected:
pgrep Xorg | xargs protect -p
Protect all ssh sessions and their child processes:
pgrep sshd | xargs protect -dip
Remove protection from all current and future processes:
protect -cdi -p 1
Using ps(1) to check if the protect flag has been applied to the process:
ps -O flags,flags2 -p 64430

DIAGNOSTICS protect: procctl: Operation not permitted The protect command does not have the required permissions to protect selected processes. There are many reasons why this could be the case, e.g.:
- protect is not executed by root.
- protect is executed inside a jail(8), which is not supported at the moment.
SEE ALSO ps(1), procctl(2), rc.conf(5)
BUGS If you protect a runaway process that allocates all memory the system will deadlock.
FreeBSD 14.0-RELEASE-p11 July 12, 2022 FreeBSD 14.0-RELEASE-p11