---
name: "psignal"
section: "9"
platform: "linux"
package: "freebsd-manpages"
version: "6.0-5"
release: "Debian 4.0 (Etch)"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/psignal/9"
---

# psignal(9)

post signal to a process or process group

## NAME

**psignal**, **pgsignal**, **gsignal** – post signal to a process or process group

## SYNOPSIS

**#include \<sys/types.h\>**

**#include \<sys/signalvar.h\>**

*void*\

**psignal**(*struct proc \*p*, *int signum*);

*void*\

**pgsignal**(*struct pgrp \*pgrp*, *int signum*, *int checkctty*);

*void*\

**gsignal**(*int pgid*, *int signum*);

## DESCRIPTION

These functions post a signal to one or more processes. The argument *signum* common to all three functions should be in the range \[1-NSIG\].

The **psignal**() function posts signal number *signum* to the process represented by the process structure *p*. With a few exceptions noted below, the target process signal disposition is updated and is marked as runnable, so further handling of the signal is done in the context of the target process after a context switch. Note that **psignal**() does not by itself cause a context switch to happen.

The target process is not marked as runnable in the following cases:

- The target process is sleeping uninterruptibly. The signal will be noticed when the process returns from the system call or trap.

- The target process is currently ignoring the signal.

- If a stop signal is sent to a sleeping process that takes the default action (see [sigaction(2)](/sigaction/2.md)), the process is stopped without awakening it.

- SIGCONT restarts a stopped process (or puts them back to sleep) regardless of the signal action (e.g., blocked or ignored).

If the target process is being traced **psignal**() behaves as if the target process were taking the default action for *signum*. This allows the tracing process to be notified of the signal.

The **pgsignal**() function posts signal number *signum* to each member of the process group described by *pgrp*. If *checkctty* is non-zero, the signal will be posted only to processes that have a controlling terminal. **pgsignal**() is implemented by walking along the process list headed by the field pg\_members of the process group structure pointed at by *pgrp* and calling **psignal**() as appropriate. If *pgrp* is NULL no action is taken.

The **gsignal**() function posts signal number *signum* to each member of the process group identified by the group id *pgid*. **gsignal**() first finds the group structure associated with *pgid*, then invokes **pgsignal**() with the argument *checkctty* set to zero. If *pgid* is zero no action is taken.

## SEE ALSO

[sigaction(2)](/sigaction/2.md), [signal(9)](/signal/9.md), [tsleep(9)](/tsleep/9.md)