Linux FAQ
This is my very personal Linux FAQ (well, actually Once-Answered-Questions,
but FAQ ist a more common term). As it is found by Google, it my help you.
Please no flames for not beeing beginners-friendly. This is a list from an
expert to experts focused on the very core of the problems.
(Myself, I am getting embaressed about solutions to problems that describe
how to use a configuration GUI while the problem is just to pick the right
driver module or give the right parameters)
Any feedback is highly welcome, please write to
"Peter J. Weyers" <linux-faq(a)usr-local.org>.
Further questions (even beginners ;-) ) might be answered too!
Q: Why do I get sometimes the error "Session management error: Could not open
network socket" when running some X11 applications within screen?
A: Gnome stores the socketname of the session manager in the environment
variable "SESSION_MANAGER". If you reuse you re-attach your screen
session after restarting gnome, this setting is out-of-date
Q: I have a binary, that can be seen with file and ls, but when starting
it or trying to analyze the problem with ldd, I get an "No such file or
directory " error:
(root) ~ # which me
/usr/local/bin/me
(root) ~ # ll /usr/local/bin/me
-rwxr-xr-x 1 peter users 115096 Feb 2 13:39 /usr/local/bin/me*
(root) ~ # /usr/local/bin/me
zsh: no such file or directory: /usr/local/bin/me
(root) ~ # ldd /usr/local/bin/me
/usr/bin/ldd: /usr/local/bin/me: No such file or directory
A: Very strange indeed. I had this once and it was resolved by installing
ldso (old dynamic linker) and libc5
Q: Adobe Reader as well as its Mozilla plugin start with the error message
"There was an error while loading the plug-in 'PPKLite.api'. The plug-in
failed to initialize."
A: Follow the Readme: symlink libldap.so.X and libber.so.X to
libldap.so and libber.so respectivly into the directory
<Installation Directory>/Reader/intellinux/lib
Q: Sometime XMMS hangs forever ...
A: There's been a discussion on futex_wait problems with xmms on the
kernel mailing list. You can check wether you have such kind of problem
by attaching strace to the hanging xmms process:
strace -p <pid of xmms>
I havn't enough experience with it yet, but maybe the following way of
starting XMMS is a workaround:
LD_ASSUME_KERNEL=2.4.19 xmms
Q: How can I find out the environment settings of a running process?
A: Do a
cat /proc/<PID of process>/environ|xargs -0 -n 1 echo
Q: Strange characters of filenames in GTK, GTK2 or GNOME applications ...
A: Try setting G_FILENAME_ENCODING to @locale
Q: Since upgrading to Kernel 2.6.17.11, fuse seems not to work any more ...
A: Check the documentation on Documentation/Changes in your kernels
source tree as it is written in the kernel config's help screen:
Needs libfuse 2.4.0 or later. Absolute minimum is 2.3.0 but mount
options 'direct_io' and 'kernel_cache' won't work.
Q: After upgrading to kernel 2.6.17.11, starting XFree86 with NVIDIA driver
and using Synaptics driver for the core pointer fails.
A: For me, the following worked:
1. Use /dev/input/mouse0 in core pointer section
2. Make sure hotplug is stopped (propably the point is to unload usbhid)
3. Load event device module (modprobe evdev)
4. Load PS/2 mouse driver module (modprobe psmouse)
5. Start hotplug
6. Start XFree86
Q: After enabling exif rotatin in gimageview (gimv) 0.2.27 it crashes now
and then ...
A: The following patch seems to mitigate the problem to a gtk error:
--- src/gimv_image_view.c.orig 2006-10-09 18:55:31.000000000 +0200
+++ src/gimv_image_view.c 2006-10-09 19:02:03.000000000 +0200
@@ -1824,7 +1824,7 @@
ExifByteOrder byte_order;
ExifShort v_short;
- g_return_val_if_fail (info->filename && *(info->filename), 0);
+ g_return_val_if_fail ( (int)info && info->filename && *(info->filename), 0);
jdata = jpeg_data_new_from_file (info->filename);
if (!jdata) {
Ah, ... well. Yes, you have to get the sources and recompile. Sorry, dude.
Q: X11 selction does not work as I am used to ...
A: You do not have - by any chance - weird (i.e. dead, double) instances
of x2x running?
Q: How do I turn on disk quota on a debian systems with only quota version 1 enabled?
A: Do as root:
aptitude install quotatool
quotacheck -M -g -F vfsold /
quotacheck -M -u -F vfsold /
/etc/init.d/quota start
to set e.g. group quotas to 2800 MB with a hard limit of 3000 MB for group
"users" do:
quotatool -g users -b -l 3000M -q 2800M -v /
and check with
quota -g users
Q: After upgrading to exim3 I get a lot of "failed to open DB file
/var/spool/exim/db/retry: File exists" errors in my exim cron jobs.
A: Run
db3_upgrade /var/spool/exim/db/retry
db3_upgrade /var/spool/exim/db/wait-remote_smtp_smarthost
as root.
Q: How do I remove the passphrase from a RSA key with openssl?
A: Try
openssl rsa -in rsa-key.pem -out rsa-key-insecure.pem
Q: I am using "noresume2" at the kernel command line, but the booting kernel
throws warnings about suspend2 nevertheless ...
A: Using "resume2=off" worked for me ...
Q: After upgrading from nfs-user-server to nfs-kernel-server mounted
directories do not show up in the exported filesystem tree any more ...
A: Do an extra entry for each local mounted filesystem in /etc/exports and
give them the "nohide" option.
Q: How do I get the mapping of USB devices to device nodes (like
/dev/input/mouse0 or /dev/sdb) if I don't want to use udev?
A: In general, if you have udev installed, the scripts below /etc/udev/scripts might give you some hints.
E.g. for /dev/input, have a look into /proc/bus/input/devices, for
usb-storage devices, the symlink /sys/block/sdb/device/ is very promising
