---
name: "modules.conf"
section: "5"
platform: "linux"
package: "modutils"
version: "2.4.27.0-6"
release: "Debian 4.0 (Etch)"
platforms: ["linux"]
url: "https://new.carta.tech/modules.conf"
---

# modules.conf(5)

configuration file for loading kernel modules

## NAME

modules.conf - configuration file for loading kernel modules

## DESCRIPTION

The behavior of **[modprobe(8)](/modprobe/8.md)** (and **[depmod(8)](/depmod/8.md)** ) can be modified by the (optional) configuration file **/etc/modules.conf.**

The configuration file consists of a set of lines.\
 All empty lines, and all text on a line after a '#', will be ignored.\
 Lines may be continued by ending the line with a '\\'.\
 The remaining lines should all conform to one of the following formats:

```
  [add] above module module_list
  alias alias_name result
  [add] below module module_list
  define VARIABLE WORD
  depfile=A_PATH
  else
  elseif EXPRESSION
  endif
  if EXPRESSION
  include PATH_TO_CONFIG_FILE
  insmod_opt=GENERIC_OPTIONS_TO_INSMOD
  install module command ...
  keep
  [add] options module MODULE_SPECIFIC_OPTIONS
  path=A_PATH
  path[TAG]=A_PATH
  generic_stringfile=A_PATH
  pcimapfile=A_PATH
  isapnpmapfile=A_PATH
  usbmapfile=A_PATH
  parportmapfile=A_PATH
  ieee1394mapfile=A_PATH
  pnpbiosmapfile=A_PATH
  [add] probe name module_list
  [add] probeall name module_list
  prune filename
  post-install module command ...
  post-remove module command ...
  pre-install module command ...
  pre-remove module command ...
  remove module command ...
  persistdir directory_name
```

All arguments to a directive will be processed to handle shell meta-characters, which means that "shell tricks" like wild-cards and commands enclosed in back-quotes can be used:

```
  path[misc]=/lib/modules/1.1.5?/local
  path[net]=/lib/modules/`uname -r`/net
```

**DANGER:** Applying shell expansion to user supplied input is a major security risk.  Modutils code only does meta expansion via shell commands for trusted data.  Basically this means only for data in the config file. Even that assumes that the user cannot run modprobe as root while supplying their own config file.  Programs (including the kernel) that invoke modutils programs as root with user supplied input must pass exactly one user supplied parameter and must set safe mode or risk creating local root exploits.  See *modprobe* for details on safe mode.

Directives may be repeated multiple times. Note that some directives can have an optional prefix: *add.* When this prefix is used, the new module\_list will be **added** to the previous module\_list instead of replacing it.

All commands (in *post-install*, *post-remove*,  *pre-install*, *pre-remove*, and *remove*) are executed using the **system()** call. Commands need to be posixly correct, as they will be processed by **/bin/sh**.

Notice that in systems running Debian GNU/Linux, this file is automatically generated by the script **update-modules** based on the contents in **/etc/modutils/**. If you want to manage this file by yourself make sure you remove the first header line which indicates to the script that it can regenerate it. If you don't, your local changes will be lost on package upgrade. Instead of modifying this file you should modify the content of files under the **/etc/modutils/** directory.

## SEMANTICS

**A\_PATH** is the fully qualified path to the target. It is possible to use shell meta-characters in **A\_PATH** including command output, such as *\`uname -r\`* and *\`kernelversion\`.*\
 These two commands are also understood internally in these utilities as meaning the version number of the current kernel and the current kernel version respectively (e.g.: 2.2.3 and 2.2).

**WORD** is a sequence if non-white characters. If ' " or \` is found in the string, all characters up to the matching ' " or \` will also be included, even whitespace. Every **WORD** will then be expanded w.r.t. meta-characters. If the expanded result gives more than one word then only the first word of the result will be used.

EXPRESSION below can be:

- *WORD compare\_op WORD*

  where compare\_op is one of ==, !=, \<, \<=, \>= or \>. The string values of the WORDs are compared.

- *-n WORD compare\_op WORD*

  where compare\_op is one of ==, !=, \<, \<=, \>= or \>. The numeric values of the WORDs are compared.

- *WORD*

  If the expansion of WORD fails, or if the expansion is "0" (zero), "false" or "" (empty) then the expansion has the value FALSE. Otherwise the expansion has the value TRUE

- *-f FILENAME*

  Test if the file FILENAME exists.

- *-k*

  Test if "autoclean" is enabled (i.e. called from the kernel).

- *! EXPRESSION*

  A negated expression is also an expression.

## SYNTAX

This is a description of the legal directives.

- *define VARIABLE WORD*

  Do a *putenv("VARIABLE=WORD").* Variables can be created and modified by this directive. The variables will be available in the environment, which makes them usable for all commands executed in the current session.

- *depfile=A\_PATH*

  This is the path to the dependency file that will be created by **depmod** and used by **modprobe** to find the modules and their dependent modules. Normally the default value should be used, see below.

- *if EXPRESSION*

  If the expression is evaluated to be **TRUE** then all directives up to the matching *else, elseif* or *endif* are processed.  Otherwise they are ignored. *if* directives may be nested up to an internal maximum of 20.\
   Note: please avoid having any **path** directives conditionally processed. Since **modprobe** has enough built-in "smarts", a conditionally processed **path** directive will gain you nothing but confusion.  Really.

- *else*

  If the previous matching *if* or *elseif* directive evaluated its expression to be **FALSE** then the directives enclosed by the (optional) *else* directive and its matching *endif* directive will be processed.

- *elseif EXPRESSION*

  If the previous matching *if* or *elseif* directives evaluated their expression to be **FALSE** and if the expression for this directive evaluates to **TRUE** then the directives up to the next matching *elseif, else* or *endif* directive will be processed.

- *endif*

  This directive ends the chain of matching *if, elseif* or *else* directive(s) controlling the conditional processing of configuration file directives.

  ```
    if EXPRESSION
        any config lines
    elseif EXPRESSION
        any config lines
    else
        any config lines
    endif
  ```

  The *else* and *elseif* directives are optional.

- *include PATH\_TO\_CONFIG\_FILE*

  To handle different platforms or configurations with a single configuration file can be quite complex. With the use of the *include* directive, conditionally processed by *if* directives, this is now easier to handle.

- *insmod\_opt=GENERIC\_OPTIONS\_TO\_INSMOD*

  If insmod should need some special options, not specified elsewhere, this directive makes it possible to add such an option, to be used for every invocation. The standard default options to insmod does normally not have to be modified unless some special situation needs to be handled.

- *keep*

  If this word is found on a line **before** any lines that contain the **path** descriptions, the default set of paths will be saved, and thus added to. Otherwise the normal behavior is that the default set will be **replaced** by the set of paths in the configuration file.

- *path=A\_PATH*

  - *path\[TAG\]=A\_PATH*

  The **A\_PATH** argument specifies an additional directory to search for modules. The **path** directive can carry an optional tag. This tells us a little more about the purpose of the modules in this directory and allows some automated operations by **modprobe.** The tag is appended to the "path" keyword enclosed in square brackets. If the tag is missing, the tag "misc" is assumed.\
   One very useful tag is **boot,** which can be used to mark all directories containing modules that should be loaded at boot-time.\
   Note that you must specify the **keep** directive to prevent any **path** directives from over-riding the default paths.

- *generic\_stringfile=A\_PATH*

  This is the path to the generic\_string file that will be created by **depmod** and used by install scripts that need string information from modules. Normally the default value should be used, see below. *pcimapfile=A\_PATH* This is the path to the pcimap file that will be created by **depmod** and used by install scripts to find the module that supports a pci device. Normally the default value should be used, see below.

- *isapnpmapfile=A\_PATH*

  This is the path to the isapnpmap file that will be created by **depmod** and used by install scripts to find the module that supports an ISA PNP device. Normally the default value should be used, see below.

- *usbmapfile=A\_PATH*

  This is the path to the usbmap file that will be created by **depmod** and used by install scripts to find the module that supports an USB device. Normally the default value should be used, see below.

- *parportmapfile=A\_PATH*

  This is the path to the parportmap file that will be created by **depmod** and used by install scripts to find the module that supports an parport device. Normally the default value should be used, see below.

- *ieee1394mapfile=A\_PATH*

  This is the path to the ieee1394map file that will be created by **depmod** and used by install scripts to find the module that supports an ieee1394 device. Normally the default value should be used, see below.

- *pnpbiosmapfile=A\_PATH*

  This is the path to the pnpbiosmap file that will be created by **depmod** and used by install scripts to find the module that supports an pnpbios device. Normally the default value should be used, see below.

- *alias alias\_name result*

  The "alias" directive can be used to give alias names to modules. A line in /etc/modules.conf that looks like this:

  ```
    alias iso9660 isofs
  ```

  makes it possible to write **modprobe iso9660** although there is no object file for such a module available.\
   Note that the line:

  ```
    alias some_module off
  ```

  will make modprobe ignore requests to load that module. Another special alias is:

  ```
    alias some_module null
  ```

  which will make requests for some\_module always succeed, but no module will actually be installed. This can be used as a base for stacks created via the *above* and *below* directives.\

  ```

  ```

  It is possible to have a large number of levels of *alias* directives, since all aliases will be recursively expanded in order to find the physical module actually referred to.  There is an arbitrary limit of 1000 on alias depth to detect loops like:

  ```
    alias a b
    alias b a
  ```

  If the final result of an *alias* mapping does not match the name of any module then modprobe applies probe and probeall mappings to the result.  If those do not succeed then the module is not found.  This makes constructs like this give sensible results (from devfs).\

  ```
    alias           /dev/sg*        /dev/sg
    probeall        /dev/sg         scsi-hosts sg
  ```

  It is legal for an alias to map module A to module B and for module A to exist at the same time but this construct is ambiguous and is **not** recommended.  For historical reasons, the kernel sound system has a module called sound.o but the sound developers also want an alias from sound to the module for the user's sound card, e.g. "alias sound sb". In an attempt to support this requirement but still maintain the defined behavior where options can be applied to aliases, modprobe bypasses alias expansion when processing a module name if the name was obtained via modules.dep, otherwise aliases are expanded.  This is not guaranteed to give the expected behavior on all combinations of aliases and real modules, you should avoid using an alias with the same name as a real module.

- *\[add\] probe name module\_list*

  - *\[add\] probeall name module\_list*

  These directives can only be used when *name* is the name of the module requested on the command line of **modprobe.** The effect is that when a request for *name* is made, the modules in module\_list will be tried, in the specified order. The difference between the directives is that *probe* will continue until the first successful module insertion, while *probeall* will continue until the end of the list. The exit status reflects whether any module has been successfully installed or not. The optional *add* prefix adds the new list to the previous list instead of replacing it.

- *prune filename*

  The top level module directory for a kernel install contains files which are not modules.  These include modules.dep, modules.generic\_string, modules.pcimap, modules.isapnpmap, modules.usbmap, modules.parportmap, modules.ieee1394map, modules.pnpbiosmap, the build symlink to the kernel source tree and any other files that the install process wants to save from a kernel build. To prevent **depmod** issuing warnings about "not an ELF file", these non-module files should appear in the prune list. **depmod** has a built in prune list which cannot be removed because it lists files which will exist for any kernel build.  If you add your own files to the top level modules directory, add a *prune* statement for each *filename*. **Note:** The prune list is only used when scanning the top directory of a *path*, and only if the directory contains at least one subdirectory from the standard list of subdirectory names, i.e. it appears to be a top level directory built from a kernel install.  The *prune* list has no effect on subdirectories of a *path*.

- *\[add\] options \[-k\] module \[MODULE\_SPECIFIC\_OPTIONS\]*

  All module names, including aliased names, can have their own *options* directives. Options specified for an alias have higher priority than the options specified for more "basic" names. This rule is used to resolve conflicting *options* directives. Options given on the command line have the highest priority. If there is *-k* before the module name, then the module won't be autocleaned even if **modprobe** has been invoked with the *-k* autoclean option. The optional *add* prefix adds the new list to the previous list instead of replacing it. If the result of an *alias* is not a real module then any *options* that were constructed from the *alias* chain are discarded before invoking probe\[all\]. If any of the *MODULE\_SPECIFIC\_OPTIONS* contain characters that are special to the shell (e.g. space, comma, parentheses) then the option must be enclosed in '"..."'. The '' delimit the option in modules.conf, the "" delimit the option when it is passed to the shell.  For example,\

  ```
    abc='"def,ghi jkl (xyz)"'
  ```

- *\[add\] above module module\_list*

  This directive makes it possible for one module to "pull in" another set of modules on top of itself in a module stack, as seen in the output of the **[lsmod(8)](/lsmod/8.md)** command. The *above* directive is useful for those circumstances when the dependencies are more complex than what can be described in the **modules.dep** dependency file. This is an optimized case of the *post-install* and *pre-remove* directives. Note that failure of installing the module will not influence the exit status of **modprobe.** The optional *add* prefix adds the new list to the previous list instead of replacing it.

- *\[add\] below module module\_list*

  This directive makes it possible for one module to "push" another set of modules below itself in a module stack, as seen in the output of the **[lsmod(8)](/lsmod/8.md)** command. The *below* directive is useful for those circumstances when the dependencies are more complex than what can be described in the **modules.dep** dependency file. This is an optimized case of the *pre-install* and *post-remove* directives. Note that failure of installing the module will not influence the exit status of **modprobe.** The optional *add* prefix adds the new list to the previous list instead of replacing it.

The following directives are useful for (optionally) executing specific commands when loading and unloading a module.  Note that even aliased module names can have these directives, which will be executed in the proper order together with any directives for the unaliased module name.

- *pre-install module command*

  Execute *command* before installing the specified module. See the *below* directive as well.

- *install module command*

  Execute *command* instead of the default **insmod** when installing the specified module.

- *post-install module command*

  Execute *command* after installing the specified module. See the *above* directive as well.

- *pre-remove module command*

  Execute *command* before removing the specified module. See the *above* directive as well.

- *remove module command*

  Execute *command* instead of the default (built-in) **rmmod** when removing the specified module.

- *post-remove module command*

  Execute *command* after removing the specified module. See the *below* directive as well.

- *persistdir=directory\_name*

  When **rmmod** removes a module that contains persistent module parameters, it stores the (possibly) modified parameters underneath *directory\_name*. When **modprobe** loads a module that contains persistent module parameters, it looks under *directory\_name* for any previous values for those parameters. You must set *persistdir* to the name of a directory that is readable when modules are loaded and is writable when modules are unloaded, the default value is /var/lib/modules/persist. Many Linux distributions load their modules before mounting filesystems, this can cause problems for persistent data. If /var is a separate partition and it is mounted after modules are loaded then **insmod** has nowhere to read persistent data from. You have two choices when /var is on a separate partition.

-

  1\) Specify *persistdir* pointing at a directory in the root partition, say /lib/modules/persist.  This assumes that the root partition is writable when **rmmod** runs.

-

  2\) Load any filesystem related modules first, mount the /var partition then load the rest of the modules.  This assumes that the filesystem modules have no persistent data.

## DEFAULT CONFIGURATION

If the configuration file '/etc/modules.conf' is missing, or if any directive is not overridden, the following defaults are assumed:

  depfile=/lib/modules/\`uname -r\`/modules.dep\
   generic\_stringfile=/lib/modules/\`uname -r\`/modules.generic\_string\
   pcimapfile=/lib/modules/\`uname -r\`/modules.pcimap\
   isapnpmapfile=/lib/modules/\`uname -r\`/modules.isapnpmap\
   usbmapfile=/lib/modules/\`uname -r\`/modules.usbmap\
   parportmapfile=/lib/modules/\`uname -r\`/modules.parportmap\
   ieee1394mapfile=/lib/modules/\`uname -r\`/modules.ieee1394map\
   pnpbiosmapfile=/lib/modules/\`uname -r\`/modules.pnpbiosmap

  path\[boot\]=/lib/modules/boot\
   path\[toplevel\]=/lib/modules/\`uname -r\`\
   path\[toplevel\]=/lib/modules/\`kernelversion\`\
   path\[toplevel\]=/lib/modules/default\
   path\[toplevel\]=/lib/modules

  persistdir=/var/lib/modules/persist

There are also a set of default *alias* and *options* directives. Since this set is continuously extended, no list will be given here. The (current) default set can be viewed by using the **modprobe -c** command with an empty **/etc/modules.conf** file.

All *options* directives specify the options needed for a module, as in:

```
  modprobe de620 bnc=1
```

These options will be overridden by any options given in the **/etc/modules.conf** file, and on the **modprobe** command line.

Remember that it is possible to have an *options* directive for aliased module names as well as for the non-aliased name. This is useful for e.g. the dummy module:

```
  alias dummy0 dummy
  options dummy0 -o dummy0
```

## ALTERNATIVE CONFIGURATION FILE

For historical reasons, if /etc/modules.conf does not exist, modutils will read /etc/conf.modules instead. However the use of this historical name is deprecated and it should be replaced with /etc/modules.conf. This version of modutils issues a warning message if /etc/conf.modules exists, later versions will give an error message and refuse to load modules.

## SEE ALSO

[depmod(8)](/depmod/8.md), [modprobe(8)](/modprobe/8.md), [insmod(8)](/insmod/8.md), [update-modules(8)](/update-modules/8.md)

## AUTHOR

```
Bjorn Ekwall <bj0rn@blox.se>
Keith Owens <kaos@ocs.com.au>
```