opam-config(1) Display configuration options for packages.


opam config [OPTION]... [COMMAND] [ARG]...


This command uses OPAM state to output information on how to use installed libraries, update the PATH, and substitute variables used in OPAM packages.

Apart from opam config env, most of these commands are used by OPAM internally, and are of limited interest for the casual user.


Return the environment variables PATH, MANPATH, OCAML_TOPLEVEL_PATH and CAML_LD_LIBRARY_PATH according to the currently selected compiler. The output of this command is meant to be evaluated by a shell, for example by doing eval `opam config env`.
Configure global and user parameters for OPAM. Use opam config setup to display more options. Use --list to display the current configuration options. You can use this command to automatically update: (i) user-configuration files such as ~/.profile and ~/.ocamlinit; and (ii) global-configaration files controlling which shell scripts are loaded on startup, such as auto-completion. These configuration options can be updated using: opam config setup --global to setup the global configuration files stored in ~/.opam/opam-init/ and opam config setup --user to setup the user ones. To modify both the global and user configuration, use opam config setup --all.
exec [--] COMMAND [ARG]...
Execute COMMAND with the correct environment variables. This command can be used to cross-compile between switches using opam config exec --switch=SWITCH -- COMMAND ARG1 ... ARGn
var VAR
Return the value associated with variable VAR. Package variables can be accessed with the syntax pkg:var.
list [PACKAGE]...
Without argument, prints a documented list of all available variables. With PACKAGE, lists all the variables available for these packages.
subst FILE...
Substitute variables in the given files. The strings %{var}% are replaced by the value of variable var (see var).
Prints a summary of your setup, useful for bug-reports.
cudf-universe [FILE]
Outputs the current available package universe in CUDF format.


-a, --all
Enable all the global and user configuration options.
Use csh-compatible mode for configuring OPAM.
Name of the configuration file to update instead of ~/.profile or ~/.zshrc based on shell detection.
Use fish-compatible mode for configuring OPAM.
-g, --global
Enable all the global configuration options.
When updating the PATH variable, replace any pre-existing OPAM path in-place rather than putting the new path in front. This means programs installed in OPAM that were shadowed will remain so after opam config env
-l, --list
List the current configuration.
Do not load the auto-completion scripts in the environment.
Do not install `opam-switch-eval` to switch & eval using a single command.
Modify ~/.ocamlinit to make `#use "topfind"` works in the toplevel.
Modify ~/.profile (or ~/.zshrc if running zsh) to setup an OPAM-friendly environment when starting a new shell.
Display environment variables as an s-expression
Use sh-compatible mode for configuring OPAM.
-u, --user
Enable all the user configuration options.
Use zsh-compatible mode for configuring OPAM.


These options are common to all commands.

--color=WHEN (absent=auto)
Colorize the output. WHEN must be `always', `never' or `auto'.
Compatibility mode with OPAM 1.0
Specify user preferences for dependency solving for this run. Overrides both $OPAMCRITERIA and $OPAMUPGRADECRITERIA. For details on the supported language, and the external solvers available, see http://opam.ocaml.org/doc/Specifying_Solver_Preferences.html. A general guide to using solver preferences can be found at http://www.dicosmo.org/Articles/usercriteria.pdf. The default value is -count(down),-count(removed),-notuptodate(solution),-count(new) for upgrades, and -count(removed),-notuptodate(request),-count(down),-notuptodate(changed),-count(changed),-notuptodate(solution) otherwise.
Debug option: Save the CUDF requests sent to the solver to FILENAME-<n>.cudf.
Print debug message to stderr. This is equivalent to setting $OPAMDEBUG to "true".
Like `--debug', but allows specifying the debug level (`--debug' sets it to 1). Equivalent to setting $OPAMDEBUG to a positive integer.
Print the git version if it exists and exit.
--help[=FMT] (default=pager)
Show this help in format FMT (pager, plain or groff).
Do not install base packages (useful for testing purposes). This is equivalent to setting $OPAMNOBASEPACKAGES to a non-empty string.
OPAM will replace itself with a newer binary found at OPAMROOT/opam if present. This disables this behaviour.
-q, --quiet
Be quiet when installing a new compiler.
--root=ROOT (absent=~/.opam)
Use ROOT as the current root path. This is equivalent to setting $OPAMROOT to ROOT.
Make sure nothing will be automatically updated or rewritten. Useful for calling from completion scripts, for example. Will fail whenever such an operation is needed ; also avoids waiting for locks, skips interactive questions and overrides the OPAMDEBUG variable.
Specify the name of the external dependency solver. The default value is aspcud
Fail whenever an error is found in a package definition or a configuration file. The default is to continue silently if possible.
Use SWITCH as the current compiler switch. This is equivalent to setting $OPAMSWITCH to SWITCH.
--use-internal-solver, --no-aspcud
Force use of internal heuristics, even if an external solver is available.
-v, --verbose
Be more verbose. Show output of all sub-commands. This is equivalent to setting $OPAMVERBOSE to "true".
Show version information.
-y, --yes
Disable interactive mode and answer yes to all questions that would otherwise be asked to the user. This is equivalent to setting $OPAMYES to "true".


OPAM makes use of the environment variables listed here. Boolean variables should be set to "0", "no" of "false" to disable, "1", "yes" or "true" to enable.

OPAMCOLOR, when set to always or never, sets a default value for the --color option.

OPAMCRITERIA specifies user preferences for dependency solving.The default value is -count(removed),-notuptodate(request),-count(down),-notuptodate(changed),-count(changed),-notuptodate(solution). See also option --criteria

OPAMCURL can be used to define an alternative for the 'curl' command-line utility to download files.

OPAMDEBUG see options `--debug' and `--debug-level'.

OPAMEXTERNALSOLVER see option `--solver'.

OPAMJOBS sets the maximum number of parallel workers to run.

OPAMNOASPCUD see option `--no-aspcud'.

OPAMNOSELFUPGRADE see option `--no-self-upgrade'.

OPAMROOT see option `--root'. This is automatically set by `opam config env --root=DIR' when DIR is non-default.

OPAMSOLVERTIMEOUT change the time allowance of the internal solver.

OPAMSWITCH see option `--switch'. Automatically set by `opam config env --switch=SWITCH'.

OPAMUPGRADECRITERIA specifies user preferences for dependency solving when performing an upgrade. Overrides OPAMCRITERIA in upgrades if both are set.The default value is -count(down),-count(removed),-notuptodate(solution),-count(new). See also option --criteria

OPAMUTF8MSGS use nice UTF8 characters in OPAM messages.

OPAMVERBOSE see option `--verbose'.

OPAMVAR_var overrides the contents of the variable var when substituting `%{var}%` strings in `opam` files.

OPAMVAR_package_var overrides the contents of the variable package:var when substituting `%{package:var}%` strings in `opam` files.

OPAMUSEINTERNALSOLVER see option `--use-internal-solver'.

OPAMYES see option `--yes'.


See https://opam.ocaml.org.


Thomas Gazagnaire <[email protected]>

Anil Madhavapeddy <[email protected]>

Fabrice Le Fessant <[email protected]>

Frederic Tuong <[email protected]>

Louis Gesbert <[email protected]>

Vincent Bernardoff <[email protected]>

Guillem Rieu <[email protected]>

Roberto Di Cosmo <[email protected]>


Check bug reports at https://github.com/ocaml/opam/issues.