opam(1) source-based OCaml package management


opam COMMAND ...


OPAM is a package manager for OCaml. It uses the powerful mancoosi tools to handle dependencies, including support for version constraints, optional dependencies, and conflict management.

It has support for different remote repositories such as HTTP, rsync, git, darcs and mercurial. It handles multiple OCaml versions concurrently, and is flexible enough to allow you to use your own repositories and packages in addition to the central ones it provides.

Use either opam <command> --help or opam help <command> for more information on a specific command.


An alias for show.
An alias for repository.
An alias for remove.
An alias for pin remove.


Display configuration options for packages.
Display help about OPAM and OPAM commands.
Initialize OPAM state.
Install a list of packages.
Checks and validate package description ('opam') files.
Display the list of available packages.
Pin a given package to a specific version or source.
Reinstall a list of packages.
Remove a list of packages.
Manage OPAM repositories.
Search into the package list.
Display information about specific packages.
Get the source of an OPAM package.
Manage multiple installation of compilers.
Update the list of available packages.
Upgrade the installed package to latest version.


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.