The abbreviation UCI stands for Unified Configuration Interface and is intended to centralize the configuration of OpenWrt.

Configuration should be easy and straightforward, making life easier! UCI is all about that. It is the successor to the NVRAM-based configuration found in the White Russian series of OpenWrt. UCI can be seen as OpenWrt's main configuration user interface for the most important system settings. Typically, these are settings that are crucial for the functioning of the device, such as are typically found in the web interface of routers and embedded devices; that is, functionality that is integrated in the system builds. Examples are the main network interface configuration, wireless settings, logging functionality and remote access configuration.

In addition, selected third party programs have been made compatible with the UCI system, so these can be managed more easily as well. Many programs have their own configuration files lying around somewhere, like/etc/network/interfaces, /etc/exports, /etc/dnsmasq.conf or /etc/samba/smb.conf and they often use different syntaxes. With OpenWrt, you don't have to bother with any of them and need to change only the UCI configuration file(s). Of course, most of the software that you would like to install will not have been prepared for UCI configuration, which is a good thing, because oftentimes you will want the full power of an application's own configuration interface, as it was intended by the developers. Therefore, only a few selected programs which benefit from availability of a centralised configuration have been made UCI-compatible by the OpenWrt package maintainers (see the UCI configuration file list below).

Most applications (save some that are made in-house) are made UCI-compatible by the package maintainer by simply writing the original configuration file (which is read by the program) according to the chosen settings in the corresponding UCI file. This is done upon running the initialization scripts in /etc/init.d/. See Init scripts for more information. Thus, when starting a daemon with such an UCI-compatible initialization script, you should be aware that the program's original configuration file gets overwritten. For example, in the case of Samba/CIFS, the file /etc/samba/smb.conf is overwritten with UCI settings from the UCI configuration file /etc/config/samba when running/etc/init.d/samba start. In addition, the application's configuration file is often stored in RAM instead of in flash, because it does not need to be stored in non-volatile memory and it is rewritten after every change, based on the UCI file. There are ways to disable UCI in case you want to adjust settings in the original configuration file not available through UCI.  add the recommended way please, or link to it.

For those non-UCI compatible programs, there is a convenient list of some non-UCI configuration files you may want to tend to. Note that, for most third party programs, you should consult the program's own documentation.

OpenWrt's central configuration is split into several files located in the /etc/config/ directory. Each file relates roughly to the part of the system it configures. You can edit the configuration files with a text editor or modify them with the command line utility program uci. UCI configuration files are also modifiable through various programming APIs (like Shell, Lua and C), which is also how web interfaces like LuCI make changes to the UCI files.

Upon changing a UCI configuration file, whether through a text editor or the command line, the services or executables that are affected must be (re)started by an init.d call, such that the updated UCI configuration is applied to them. Many programs are made compatible with UCI in this way by making their init.d script write their standard software specific configuration files. The init.d script first properly writes such a configuration file to the software's expected location and it is read in again by restarting the executable. Note that just (re)starting the executable directly, without init.d calls, will not result in an UCI update to relegate UCI config to the program's expectedconfiguration file. Changes in files in /etc/config/ then take no effect.

As an example of modifying the UCI configuration, suppose you want to change the device's IP address from the default 192.168.1.1 to 192.168.2.1. To do this, using any text editor, such as vi, change the line

option ipaddr 192.168.1.1

in the file /etc/config/network to:

option ipaddr 192.168.2.1

Next, commit the settings by running

/etc/init.d/network restart

In this case, remember that you have to login again using SSH as the device is now accessible at its new IP address!

The UCI configuration files usually consist of one or more config statements, so called sections with one or more option statements defining the actual values.

Below is an example of a simple configuration file:

package 'example'config 'example' 'test'option   'string'      'some value'option   'boolean'     '1'list     'collection'  'first item'list     'collection'  'second item'

• The  config 'example' 'test' statement defines the start of a section with the type  example and the name  test. There can also be so called anonymous sections with only a type, but no name identifier. The type is important for the processing programs to decide how to treat the enclosed options.

• The  option 'string' 'some value' and  option 'boolean' '1' lines define simple values within the section. Note that there are no syntactical differences between text and boolean options. Per convention, boolean options may have one of the values '0', 'no', 'off' or 'false' to specify a false value or '1' , 'yes', 'on' or 'true' to specify a true value.

• In the lines starting with a  list keyword an option with multiple values is defined. All  list statements that share the same name,  collection in our example, will be combined into a single list of values with the same order as in the configuration file.

• The indentation of the  option and  list statements is a convention to improve the readability of the configuration file but it's not syntactically required.

• If an option is absent and not required, the default value is assumed. If it is absent and required, it may trigger an error in the application or other unwanted behaviour.

Usually you do not need to enclose identifiers or values in quotes. Quotes are only required if the enclosed value contains spaces or tabs. Also it's legal to use double- instead of single-quotes when typing configuration options.

All of the examples below are valid UCI syntax:

• option example value
• option 'example' value
• option example "value"
• option "example" 'value'
• option 'example' "value"

In contrast, the following examples are not valid UCI syntax:

• option 'example" "value' (quotes are unbalanced)
• option example some value with space (note the missing quotes around the value)

It is important to know that UCI identifiers and config file names may contain only the characters a-z, 0-9 and _. E.g. no hyphens (-) are allowed. Option values may contain any character (as long they are properly quoted).

For adjusting settings, one normally changes the UCI config files directly. However, for scripting purposes, all of UCI configuration can also be read and changed using the ucicommand line utility. For developers requiring automatic parsing of the UCI configuration, it is therefore redundant, unwise, and inefficient to use awk and grep to parse OpenWrt's config files. The uci utility offers all functionality with respect to modifying and parsing UCI.

Below is the usage, as well as some useful examples of how to use this powerful utility.

When using uci to write configuration files, the files are always rewritten in whole and non-recognised commands are omitted. This means that any extraneous lines in the file are deleted, such as comments. If you have UCI configuration files that you have edited yourself and you want to preserve your own comments and blank lines, you should not use the command line utility but edit the files normally. Note that some files, such as the uHTTPd configuration file, already contain many comments when the application is first installed. Also, note that some applications such as LuCI also use the uci utility and thus may rewrite UCI configuration files.

When there are multiple rules next to each other, UCI uses array-like references for them. If there are 8 NTP servers, UCI will let you reference their sections astimeserver.@timeserver[0] for the first or timeserver.@timeserver[7] for the last one. You can also use negative indexes, such as timeserver.@timeserver[-1]. "-1" means the last one, "-2" means the second-to-last one, and so on. This comes in very handy when appending new rules to the end of a list. See the examples below.

root@OpenWrt:/lib/config#uci

Usage: uci [<options>] <command> [<arguments>]Commands:batchexport     [<config>]import     [<config>]changes    [<config>]commit     [<config>]add        <config> <section-type>add_list   <config>.<section>.<option>=<string>show       [<config>[.<section>[.<option>]]]get        <config>.<section>[.<option>]set        <config>.<section>[.<option>]=<value>delete     <config>[.<section[.<option>]]rename     <config>.<section>[.<option>]=<name>revert     <config>[.<section>[.<option>]]Options:-c <path>  set the search path for config files (default: /etc/config)-d <str>   set the delimiter for list values in uci show-f <file>  use <file> as input instead of stdin-m         when importing, merge data into an existing package-n         name unnamed sections on export (default)-N         don't name unnamed sections-p <path>  add a search path for config change files-P <path>  add a search path for config change files and use as default-q         quiet mode (don't print error messages)-s         force strict mode (stop on parser errors, default)-S         disable strict mode-X         do not use extended syntax on 'show'

If we want to change the listening port of the uHTTPd Web Server from 80 to 8080 we change the configuration in /etc/config/uhttpd :

Done, now the configuration file is updated and uHTTPd listens on port 8080.

"uci add blah" will create a new _anonymous_ section of type blah. ie,

If you actually want a named section of that type, for instance,

Then "uci add" cannot be used, instead, use this synt

Consider this example config file:

Then the paths below are equal in every group:

If you show it, you get :

But if you used "uci show foo.@bar[0]", you will see:

#uci show foo.@bar[0]foo.first=barfoo.first.name=Mr. First

This is a good example of both adding a firewall rule to forward the TCP SSH port, and of the negative (-1) syntax used with uci.

• Backfire

  uci -P/var/state get network.wan.ipaddr

• The uci state vars are deprecated and not used anymore for network related information. In Trunk (not really uci) do

  . /lib/functions/network.sh; network_get_ipaddr ip wan; echo $ip

• Backfire

  uci -P/var/state get network.wan.ifname

• The uci state vars are deprecated and not used anymore for network related information. In Trunk (not really uci) do

  . /lib/functions/network.sh; network_get_device if_wan wan; echo $if_wan

• Or

  . /lib/functions/network.sh; network_get_physdev if_wan wan; echo $if_wan

 uci get wireless.@wifi-iface[-1].ssid

To set some system defaults the first time the device boots, create a script in the folder

/etc/uci-defaults/

All scripts in that folder are automatically executed by  /etc/init.d/boot and if they exited with code 0  deleted afterwards (scripts that did not exit with code 0 are not deleted and will be re-executed during the next boot until they also successfully exit).

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