setsid: add page (#7841)

* setsid: add page

* Use "exit code" instead of "return value"

Co-authored-by: pixel <chrissx@chrissx.de>

Co-authored-by: pixel <chrissx@chrissx.de>

pages/linux/setsid.md

@@ -0,0 +1,25 @@
+# setsid
+
+> Run a program in a new session if the calling process is not a process group leader.
+> The created session is by default not controlled by the current terminal.
+> More information: <https://manned.org/setsid>.
+
+- Run a program in a new session:
+
+`setsid {{program}}`
+
+- Run a program in a new session discarding the resulting output and error:
+
+`setsid {{program}} > /dev/null 2>&1`
+
+- Run a program creating a new process:
+
+`setsid --fork {{program}}`
+
+- Return the exit code of a program as the exit code of setsid when the program exits:
+
+`setsid --wait {{program}}`
+
+- Run a program in a new session setting the current terminal as the controlling terminal:
+
+`setsid --ctty {{program}}`