| Stephen Gran on 5 Jan 2004 23:55:02 -0000 |
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On Mon, Jan 05, 2004 at 06:08:35PM -0500, gabriel rosenkoetter said: > On Mon, Jan 05, 2004 at 02:53:31PM -0500, Stephen Gran wrote: > > portable and feed it back to upstream. Any pointers towards something > > truly portable would be great. Again, people with other platforms > > (hint) are a big help, because I don't have access to them myself. > > Well, getppid(2) seems like the Right way to do this, and various > shells provide direct access to it's output (it's $PPID in zsh, for > instance). This was my feeling, but this is what troubled me with using it: (logged in on console, tty2) steve:~$ ps ax | grep bash 1566 tty2 R 0:00 -bash 1596 pts/0 S 0:00 -bash 1612 pts/2 S 0:00 /bin/bash 1641 pts/3 S 0:00 /bin/bash 1650 pts/3 S 0:00 /bin/bash steve:~$ echo $PPID 1 steve:~$ cat > PPID echo "PPID = $PPID" steve:~$ sh PPID PPID = 1566 steve:~$ So checking $PPID from within a script works, but appears to return 1 when run from the console. I understand that init launches getty, which then launches bash when I log in, but I would have thought that the pid of the getty process should have been the value in $PPID. Maybe I misunderstand getty, though (entirely possible), and it is really that init spawns a getty process to listen for a login, and then itself launches a shell when you log in. If this is the case, then my first feeling, that a simple `if [ "$PPID" = 1 ]; then ...` should be fine. I was just worried that it couldn't be that simple because of my experimenting, and probable misinterpretation of how getty and login work. It even seems like $PPID works in dash, so hopefully it's portable enough. -- -------------------------------------------------------------------------- | Stephen Gran | There are three things I always forget. | | steve@lobefin.net | Names, faces -- the third I can't | | http://www.lobefin.net/~steve | remember. -- Italo Svevo | -------------------------------------------------------------------------- Attachment:
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