Setting Up a Unix Server

We can point httpd at our site with the -d flag (notice the full pathname to the site.toddle directory, which will probably be different on your machine):

% httpd -d /usr/www/APACHE3/site.toddle

Since you will be typing this a lot, it’s sensible to copy it into a script called go . This can go in /usr/local/bin or in each local site. We have done the latter since it is convenient to change it slightly from time to time. Create it by typing:

% cat > /usr/local/bin/go
test -d logs || mkdir logs
httpd -f 'pwd'/conf/httpd$1.conf -d 'pwd'
            ^d

^d is shorthand for Ctrl-D, which ends the input and gets your prompt back. This go will work on every site. It creates a logs directory if one does not exist, and it explicitly specifies paths for the ServerRoot directory (-d) and the Config file (-f). The command ' pwd ' finds the current directory with the Unix command pwd . The back-ticks are essential: they substitute pwd’s value into the script — in other words, we will run Apache with whatever configuration is in our current directory. To accomodate sites where we have more than one Config file, we have used ...httpd$1... where you might expect to see ...httpd... The symbol $1 copies the first argument (if any) given to the command go . Thus ./go 2 will run the Config file called httpd2.conf, and ./go by itself will run httpd.conf.

Remember that you have to be in the site directory. If you try to run this script from somewhere else, pwd’s return will be nonsense, and Apache will complain that it 'could not open document config file ...'.

Make go runnable, and run it by typing the following (note that you have to be in the directory .../site.toddle when you run go):

% chmod +x go
% go

If you get the error message:

go: command not found

you need to type:

% ./go

This launches Apache in the background. Check that it’s running by typing something like this (arguments to psvary from Unix to Unix):

% ps -aux

This Unix utility lists all the processes running, among which you should find several httpds.^[1]

Sooner or later, you have finished testing and want to stop Apache. To do this, you have to get the process identity (PID) of the program httpd using ps -aux:

USER      PID %CPU %MEM   VSZ  RSS  TT  STAT STARTED      TIME COMMAND
root      701  0.0  0.8   396  240  v0  R+    2:49PM   0:00.00 ps -aux
root        1  0.0  0.9   420  260  ??  Is    8:13AM   0:00.02 /sbin/init --
root        2  0.0  0.0     0    0  ??  DL    8:13AM   0:00.04  (pagedaemon)
root        3  0.0  0.0     0    0  ??  DL    8:13AM   0:00.00  (vmdaemon)
root        4  0.0  0.0     0    0  ??  DL    8:13AM   0:02.24  (syncer)
root       35  0.0  0.3   204   84  ??  Is    8:13AM   0:00.00 adjkerntz -i
root       98  0.0  1.8   820  524  ??  Is    7:13AM   0:00.43 syslogd
daemon    107  0.0  1.3   820  384  ??  Is    7:13AM   0:00.00 /usr/sbin/portma
root      139  0.0  2.1   888  604  ??  Is    7:13AM   0:00.07 inetd
root      142  0.0  2.0   980  592  ??  Ss    7:13AM   0:00.27 cron
root      146  0.0  3.2  1304  936  ??  Is    7:13AM   0:00.25 sendmail: accept
root      209  0.0  1.0   500  296 con- I     7:13AM   0:00.02 /bin/sh /usr/loc
root      238  0.0  5.8 10996 1676 con- I     7:13AM   0:00.09 /usr/local/libex
root      239  0.0  1.1   460  316  v0  Is    7:13AM   0:00.09 -csh (csh)
root      240  0.0  1.2   460  336  v1  Is    7:13AM   0:00.07 -csh (csh)
root      241  0.0  1.2   460  336  v2  Is    7:13AM   0:00.07 -csh (csh)
root      251  0.0  1.7  1052  484  v0  S     7:14AM   0:00.32 bash
root      576  0.0  1.8  1048  508  v1  I     2:18PM   0:00.07 bash
root      618  0.0  1.7  1040  500  v2  I     2:22PM   0:00.04 bash
root      627  0.0  2.2   992  632  v2  I+    2:22PM   0:00.02 mince demo_test
root      630  0.0  2.2   992  636  v1  I+    2:23PM   0:00.06 mince home
root      694  0.0  6.7  2548 1968  ??  Ss    2:47PM   0:00.03 httpd -d /u
webuser   695  0.0  7.0  2548 2044  ??  I     2:47PM   0:00.00 httpd -d /u
webuser   696  0.0  7.0  2548 2044  ??  I     2:47PM   0:00.00 httpd -d /u
webuser   697  0.0  7.0  2548 2044  ??  I     2:47PM   0:00.00 httpd -d /u
webuser   698  0.0  7.0  2548 2044  ??  I     2:47PM   0:00.00 httpd -d /u
webuser   699  0.0  7.0  2548 2044  ??  I     2:47PM   0:00.00 httpd -d /u

To kill Apache, you need to find the PID of the main copy of httpd and then do kill <PID> — the child processes will die with it. In the previous example the process to kill is 694 — the copy of httpd that belongs to root. The command is this:

% kill 694

If ps -aux produces more printout than will fit on a screen, you can tame it with ps -aux | more — hit Return to see another line or Space to see another screen. It is important to make sure that the Apache process is properly killed because you can quite easily kill a child process by mistake and then start a new copy of the server with its children — and a different Config file or Perl scripts — and so get yourself into a royal muddle.

To get just the lines from ps that you want, you can use:

ps awlx | grep httpd

On Linux:

killall httpd

Alternatively and better, since it is less prone to finger trouble, Apache writes its PID in the file ... /logs/httpd.pid (by default — see the PidFile directive), and you can write yourself a little script, as follows:

kill 'cat /usr/www/APACHE3/site.toddle/logs/httpd.pid'

You may prefer to put more generalized versions of these scripts somewhere on your path. stop looks like this:

pwd | read path
kill 'cat $path/logs/httpd.pid'

Or, if you don’t plan to mess with many different configurations, use .../src/support/apachect1 to start and stop Apache in the default directory. You might want to copy it into /usr/local/bin to get it onto the path, or add $apacheinstalldir/bin to your path. It uses the following flags:

usage: ./apachectl (start|stop|restart|fullstatus|status|graceful|configtest|help)

When we typed ./go, nothing appeared to happen, but when we looked in the logs subdirectory, we found a file called error_log with the entry:

[<date>]:'mod_unique_id: unable to get hostbyname ("myname.my.domain")

In our case, this problem was due to the odd way we were running Apache, and it will only affect you if you are running on a host with no DNS or on an operating system that has difficulty determining the local hostname. The solution was to edit the file /etc/hosts and add the line:

10.0.0.2 myname.my.domain myname

where 10.0.0.2 is the IP number we were using for testing.

However, our troubles were not yet over. When we reran httpd, we received the following error message:

[<date>]--couldn't determine user name from uid

This means more than might at first appear. We had logged in as root. Because of the security worries of letting outsiders log in with superuser powers, Apache, having been started with root permissions so that it can bind to port 80, has attempted to change its user ID to -1. On many Unix systems, this ID corresponds to the user nobody : a supposedly harmless user. However, it seems that FreeBSD does not understand this notion, hence the error message.^[2] In any case, it really isn’t a great idea to allow Apache to run as nobody (or any other shared user), because you run the risk that an attacker exploiting the fact that various different services are sharing the same user, that is, if you are running several different services (ftp, mail, etc) on the same machine.

^[1]On System V-based Unix systems (as opposed to Berkeley-based), the command ps -ef should have a similar effect.

^[2]In fact, this problem was fixed for FreeBSD long ago, but you may still encounter it on other operating systems.