# Getpwnam issue **URL:** \ **Category:** NGINX\ **Created:** [January 4, 2011, 9:45pm UTC](https://www.ruby-forum.com/t/getpwnam-issue/201303 "2011-01-04T21:45:43Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![dubstep](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/cdc98d/32.png) [@dubstep](https://www.ruby-forum.com/u/dubstep)\ **Post date:** [January 4, 2011, 9:45pm UTC](https://www.ruby-forum.com/t/getpwnam-issue/201303/1 "2011-01-04T21:45:43Z")
Hello all, I am testing a chroot’ed nginx setup on Debian Lenny and am receiving the error: `getpwnam("www-data") failed` when I try to start nginx. My search to find a possible solution have so far been fruitless but I am hoping someone smarter than I could offer some advice. I’ve setup the “jail” in /chroot/nginx, created the relevant directory structure (/dev/, /etc, /usr, /var, etc.). Then I copied files that “ldd `which nginx`” showed as linked to the relevant directories, and also copied what I believe are the necessary /etc/\* files to /chroot/nginx/etc/. So my directory structure is basically as follows: /chroot/nginx (base chroot directory) /etc passwd, shadow, group, hosts, nsswitch.conf, resolv.conf /nginx nginx.conf, /sites-{available, enabled} /usr /sbin nginx /lib _(some shared library files here) /lib libnss\_dns_ files, libnss\_compat\* files, libnss\_files\*, and some other shared library files here /var /dev /tmp (that’s a non-exhaustive overview, but is hopefullly enough to diagnose the problem) I know that it’s not a getpwnam() issue, as I found a forum discussion which involves troubleshooting the getpwnam() function with a simple C program to ensure that getpwnam() is indeed working properly. I’ve tested this and it works as expected in a non-chroot setting (discussion is here, it’s in Russian, so you may need to use Google Translate: [Re: nginx и cygwin](http://forum.nginx.org/read.php?21,128545,129156#msg-129156)). I am using the start-stop-daemon to manage nginx with a script similar to this: [nginx startup script for Debian](http://snippets.aktagon.com/snippets/155-nginx-startup-script-for-Debian). So to start nginx I run: ``` # start-stop-daemon --start --pidfile /var/run/nginx/nginx.pid ``` –exec /usr/sbin/nginx --chroot /chroot/nginx And this is what throws the error. I think that it’s really an issue of having my paths or permissions wrong such that getpwnam() cannot read/find the passwd file, but my attempts to change permissions, owners, and paths have not been successful. Any advice or suggestions would be appreciated! Thanks, Chad Posted at Nginx Forum: > **[getpwnam issue](https://forum.nginx.org/read.php?2,163489,163489#msg-163489)** > > Hello all, I am testing a chroot'ed nginx setup on Debian Lenny and am receiving the error: \`getpwnam("www-data") failed\` when I try to start nginx. My search to find a possible solution have so far been fruitless but I am hoping someone... ---
**Author:** ![chadmiko](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/e99b99/32.png) [@chadmiko](https://www.ruby-forum.com/u/chadmiko)\ **Post date:** [January 4, 2011, 11:54pm UTC](https://www.ruby-forum.com/t/getpwnam-issue/201303/2 "2011-01-04T23:54:12Z")
I have seemingly solved this issue. I failed to copy /lib/libnsl.so.1 into my chroot /lib folder but have added it and I can start nginx using the start-stop-daemon command with the --chroot flag; strace is a life-saver. In case anyone else goes down this road in the future, you can strace your start-stop-daemon call to a chrooted nginx as follows: # start-stop-daemon --start --pidfile $PIDFILE --exec $DAEMON --chroot $CHRDIR --startas /usr/bin/strace – -f -o /tmp/$NAME.strace $DAEMON $ARGS where… $PIDFILE = path/to/nginx/pid $DAEMON = /usr/sbin/nginx $CHRDIR = /chroot/nginx (or your chroot dir) $NAME = nginx make sure you copy /usr/bin/strace into $CHRDIR/usr/bin/ else the above command will fail (don’t forget to remove it after you’ve debugged everything). strace will be output to $CHRDIR/tmp/$NAME.strace. This is how I was able to determine what libraries I needed. Posted at Nginx Forum: [http://forum.nginx.org/read.php?2,163489,163540#msg-163540](http://forum.nginx.org/read.php?2,163489,163540#msg-163540) ---
**Author:** ![chadmiko](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/e99b99/32.png) [@chadmiko](https://www.ruby-forum.com/u/chadmiko)\ **Post date:** [January 12, 2011, 10:11pm UTC](https://www.ruby-forum.com/t/getpwnam-issue/201303/3 "2011-01-12T22:11:30Z")
## chadmiko Wrote: > # start-stop-daemon --start --pidfile $PIDFILE > > make sure you copy /usr/bin/strace into > $CHRDIR/usr/bin/ else the above command will fail > (don’t forget to remove it after you’ve debugged > everything). > strace will be output to $CHRDIR/tmp/$NAME.strace. > > This is how I was able to determine what libraries > I needed. Thanks for the tip! I too was having trouble with chroot’ing nginx on Ubuntu Lucid 10.04 LTS, and that strace led me to the missing libs. To make this easier, I wrote a script based on many tips from Vivek Gite’s blog, mainly this post: [http://www.cyberciti.biz/faq/howto-run-nginx-in-a-chroot-jail/](http://www.cyberciti.biz/faq/howto-run-nginx-in-a-chroot-jail/) , and I’ve released it on Github in hopes it will help others: > **[GitHub - doublerebel/nginx-chroot: Script to chroot nginx on Ubuntu "Lucid" 10.04 LTS](https://github.com/doublerebel/nginx-chroot)** > > Script to chroot nginx on Ubuntu "Lucid" 10.04 LTS I’ve included the nginx init.d script updated to launch nginx chrooted. It also creates a new, password-locked nginx user with the home directory set to the chroot directory. I’ve only tested it with an Ubuntu 64-bit minimal installation on my VPS, so feel free to comment or submit patches on Github! Cheers, Charles Posted at Nginx Forum: [http://forum.nginx.org/read.php?2,163489,165707#msg-165707](http://forum.nginx.org/read.php?2,163489,165707#msg-165707)