Add process group management functionality to s6-setsid

1 files changed, 39 insertions, 10 deletions

diff --git a/doc/s6-setsid.html b/doc/s6-setsid.html
index 2fe991b..d5046af 100644
--- a/doc/s6-setsid.html
+++ b/doc/s6-setsid.html
@@ -18,29 +18,58 @@
 <h1> The s6-setsid program </h1>
 
 <p>
-s6-setsid runs a program as session leader.
+ s6-setsid runs a program as a new session leader, or in a new
+foreground or background process group.
 </p>
 
 <h2> Interface </h2>
 
 <pre>
-     s6-setsid [ -I | -i ] <em>prog...</em>
+     s6-setsid [ -s | -b | -f | -g ] [ -i | -I | -q ] [ -d ctty ] <em>prog...</em>
 </pre>
 
 <ul>
- <li> s6-setsid creates a new session if it is not a session leader, and becomes
-session leader of this new session. </li>
- <li> It then executes into <em>prog...</em>. </li>
+ <li> s6-setsid creates a new session, or a new process group,
+and may make that process group the foreground process group,
+depending on the options it has been given. </li>
+ <li> As session leader or process group leader, s6-setsid then
+executes into <em>prog...</em>. </li>
 </ul>
 
 <h2> Options </h2>
 
 <ul>
- <li> <tt>-i</tt>&nbsp;: strict. If s6-setsid is already a session leader, it will
-exit 111 with an error message. </li>
- <li> <tt>-I</tt>&nbsp;: loose. If s6-setsid is already a session leader, it will
-print a warning message, but exec into <em>prog</em> nonetheless. This is the
-default. </li>
+ <li> <tt>-s</tt>&nbsp;: session. s6-setsid will try and execute
+<em>prog</em> as a session leader. This is the default. </li>
+ <li> <tt>-b</tt>&nbsp;: background process group. s6-setsid will
+not create a new session, but will create a new process group, and
+try and execute <em>prog</em> as the new process group leader. </li>
+ <li> <tt>-f</tt>&nbsp;: foreground process group. s6-setsid will
+not create a new session, but will create a new process group and
+attach its session's controlling terminal to the new process group
+before executing <em>prog</em>. However, the new process group
+will likely be stopped, waiting for the former foreground process
+group to relinquish the controlling terminal, and will need to be
+sent a SIGCONT to resume. To avoid that, use the next option. </li>
+ <li> <tt>-g</tt>&nbsp;: grab terminal. s6-setsid will
+not create a new session, but will create a new process group and
+attach its session's controlling terminal to the new process group
+before executing <em>prog</em>. It will forcefully grab the controlling
+terminal from the former foreground process group, which means that
+a process belonging to the former foreground process group attempting
+to read from or write to that terminal will be stopped. </li>
+ <li> <tt>-i</tt>&nbsp;: strict. If s6-setsid cannot perform the
+operations it needs, it will exit 111 with an error message. </li>
+ <li> <tt>-I</tt>&nbsp;: loose. If s6-setsid cannot perform the operations,
+it will print a warning message, but exec into <em>prog</em> nonetheless.
+This is the default. </li>
+ <li> <tt>-q</tt>&nbsp;: silent. s6-setsid will not print any warning
+message; it will exec into <em>prog</em> even if it cannot perform the
+operations. </li>
+ <li> <tt>-d&nbsp;<em>ctty</em></tt>&nbsp;: assume <em>ctty</em> is
+the controlling terminal for the current session. Default is 0.
+This is only useful when used with the <tt>-f</tt> or
+<tt>-g</tt> options. </li>
 </ul>
 
 </body>