I accidentally deleted my .config for my kernel configuration on Linux, and seem to remember there was a way to retrieve the kernel configuration via the proc filesystem somehow.
Is this still possible, and if so how would I do it?
asked May 23, 2011 at 10:49
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2superuser.com/questions/577307/… || askubuntu.com/questions/163304/… || stackoverflow.com/questions/14376540/… || unix.stackexchange.com/questions/83319/… || serverfault.com/questions/51032/…– Ciro Santilli OurBigBook.comCommented Aug 7, 2016 at 15:44
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8 Answers
Depending on your system, you'll find it in any one of these:
/proc/config.gz/boot/config/boot/config-$(uname -r)
and possibly more places.
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4On some distros (Fedora/Redhat) it's /boot/config-2.6.18-194.el5 or similar, with the kernel release string appended.– PhilRCommented May 23, 2011 at 15:50
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1@Phil I run a distro (Zenwalk) where those filenames are symlinked by the latest kernel package to
/boot/config. I'll go ahead and add these to the list - thanks for reminding me. Commented May 23, 2011 at 20:15 -
2Not existing such files on Ubuntu Mate or Kali Linux for RaspBerry Pi. Commented Oct 5, 2017 at 23:23
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2You should mention that your first item (/proc) is only available if module "configs" is loaded– AndyCommented Feb 27, 2018 at 7:41
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3Note that you can use
zgrep CONFIG_OPTION /proc/config.gzif you want to search for a specific option without unzipping a copy of the config file. Commented Sep 25, 2020 at 6:34
For an actual running kernel, one way to get the config file this is to
cat /proc/config.gz | gunzip > running.config
or,
zcat /proc/config.gz > running.config
Then running.config will contain the configuration of the running linux kernel.
However this is only possible if your running linux kernel was configured to have /proc/config.gz. The configuration for this is found in
General setup[*] Kernel .config support[*] Enable access to .config through /proc/config.gz
Most distributions do not have this configuration set. They provide kernel config files in their kernel packages and is usually found in /boot/ directory.
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13These are known as
CONFIG_IKCONFIGandCONFIG_IKCONFIG_PROC, if you're grepping for them. Commented Mar 26, 2015 at 18:34 -
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1@nocnokneo for me that failed (offered to show me the binary file) but
zlessworked Commented Jan 22, 2021 at 21:24 -
Not true, a "normal" installation of Ubuntu 22.04 does not have a /proc/config.gz file.– simonCommented Apr 18 at 20:04
A Little bit late but maybe it helps someone. I didn't have /proc/config.gz nor /boot/config nor /boot/config-$(uname -r) on my Computer. I had to run modprobe configs as root. Then, /proc/config.gz was present
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Can confirm on Intel MIC embedded Linux (BusyBox), this is necessary and works. Commented Feb 23, 2016 at 18:59
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FATAL: Module configs not found.on OMV 2.2 (Debian Wheezy) so glad they provided it in /boot/config-$(uname -r)– tuk0zCommented Apr 12, 2016 at 11:42 -
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'modprobe configs' is very helpful I had tests that automatically probe kconfig that were failing on a Raspberry Pi 3, but now work. Thanks for the tip!!– Tim BirdCommented Jan 3, 2019 at 0:40
Regardless of the distribution, you can run: cat /lib/modules/$(uname -r)/build/.config
Source: proc(5) man page (search for /proc/config.gz).
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1Unfortunately neither this no any other solution here works to get the kernel config on a Netgear ReadyNAS. Commented Jun 8, 2022 at 19:21
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If you couldn't find kernel configuration in /boot/ nor in /proc/config.gz, you can try extracting this information from the kernel itself.
Inside any kernel source code there is a script for extracting config located in scripts/extract-ikconfig, pass the kernel you want its configuration as parameter to this script.
This solution will only work if Kernel .config support was enabled in the compiled kernel.
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2This was extremely helpful and helped me to obtain plenty of configs I didn't expect to ever see. Thanks! Commented Oct 2, 2017 at 14:16
If you can't find any of the suggested files and you are able to modprobe you should almost always be able to get a copy of the current config this way.
modprobe configs # might need `sudo modprobe configs`
# This will create /proc/config.gz
zcat /proc/config.gz
# Or if you are looking for whether a specific option was set
zgrep USBIP /proc/config.gz
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Interesting idea, but I'm not sure enough kernels ship with the configs module available. I couldn't find it on the Ubuntu 18.04 or 20.04 systems I had handy. Commented Sep 8, 2020 at 0:40
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I found it useful specifically on ChromeOS where they don't include the compressed configs but do include the module to export the running config if so desired. Commented Sep 8, 2020 at 3:02
Run modprobe configs as root to create /proc/config.gz
After that zcat /proc/config.gz > /boot/config-$(uname -r) to list config of the kernel.
For RedHat-based distributions, the .config file of the off-the-shelf kernel can be found with the command cat /lib/modules/$(uname -r)/build/.config that's available after the package kernel-devel is installed using the command:
yum -y install kernel-devel
Note that with the real Red Hat Enterprise Linux distribution, you will need to enable the source-repository to get this package. On RHEL8, use the following command to do that:
subscription-manager repos --enable=rhel-8-for-x86_64-baseos-source-rpms
