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Manual Reference Pages  -  OPAM-CONFIG (1)


opam-config - Display configuration options for packages.


Common Options
Environment Variables
Further Documentation


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.


env 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.
pef-universe [FILE]
  Outputs the current available package universe in PEF format.


-a, --all
  Enable all the global and user configuration options.
  Name of the configuration file to update instead of ~/.profile or ~/.zshrc based on shell detection.
-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, etc., depending on your shell) to setup an OPAM-friendly environment when starting a new shell.
  Display environment variables as an s-expression
--shell=SHELL (absent=sh)
  Sets the configuration mode for OPAM environment appropriate for SHELL. One of one of ‘bash’, ‘sh’, ‘csh’, ‘zsh’ or ‘fish’.
-u, --user
  Enable all the user configuration options.


These options are common to all commands.
--color=WHEN (absent=auto)
  Colorize the output. WHEN must be one of ‘always’, ‘never’ or ‘auto’.
  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 A general guide to using solver preferences can be found at The default value is -count(down),-count(removed),-notuptodate(solution),-sum(solution,version-lag),-count(new) for upgrades, and -count(removed),-notuptodate(request),-sum(request,version-lag),-count(down),-notuptodate(changed),-count(changed),-notuptodate(solution),-sum(solution,version-lag) 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. Either ’aspcud’, ’packup’ or a custom command that may contain the variables %{input}%, %{output}% and %{criteria}%
  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 package sub-commands and their output. Repeat to see more. Repeating n times is equivalent to setting $OPAMVERBOSE to "n".
  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),-sum(request,version-lag),-count(down),-notuptodate(changed),-count(changed),-notuptodate(solution),-sum(solution,version-lag). See also option --criteria

OPAMCURL can be used to select a given ’curl’ program. See OPAMFETCH for more options.

OPAMDEBUG see options ‘--debug’ and ‘--debug-level’.

OPAMDOWNLOADJOBS sets the maximum number of simultaneous downloads.

OPAMEXTERNALSOLVER see option ‘--solver’.

OPAMFETCH specifies how to download files: either ‘wget’, ‘curl’ or a custom command where variables %{url}%, %{out}%, %{retries}%, %{compress}% and %{checksum}% will be replaced. Overrides the ’download-command’ value from the main config file.

OPAMJOBS sets the maximum number of parallel workers to run.

OPAMLOCKRETRIES sets the number of tries after which OPAM gives up acquiring its lock and fails. <= 0 means infinite wait.

OPAMNO answer no to any question asked.

OPAMNOASPCUD see option ‘--no-aspcud’.

OPAMNOSELFUPGRADE see option ‘--no-self-upgrade’.

OPAMPINKINDAUTO if set, version control systems are detected when pinning to a local path.

OPAMREQUIRECHECKSUMS see option ‘--require-checksums’.

OPAMRETRY sets the number of tries before failing downloads.

OPAMROOT see option ‘--root’. This is automatically set by ‘opam config env --root=DIR’ when DIR is non-default or OPAMROOT is already defined.

OPAMSAFE see option ‘--safe’

OPAMSKIPVERSIONCHECKS bypasses some version checks. Unsafe, for compatibility testing only.

OPAMSOLVERTIMEOUT change the time allowance of the internal solver.

OPAMSTATUSLINE display a dynamic status line showing what’s currently going on on the terminal. (one of one of ‘always’, ‘never’ or ‘auto’)

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),-sum(solution,version-lag),-count(new). See also option --criteria

OPAMUSEINTERNALSOLVER see option ‘--use-internal-solver’.

OPAMUTF8 use UTF8 characters in output (one of one of ‘always’, ‘never’ or ‘auto’). By default ‘auto’, which is determined from the locale).

OPAMUTF8MSGS use extended UTF8 characters (camels) in OPAM messages. Implies OPAMUTF8. This is set by default on OSX only.

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.

OPAMVERBOSE see option ‘--verbose’.

OPAMYES see option ‘--yes’.




Thomas Gazagnaire <>

Anil Madhavapeddy <>

Fabrice Le Fessant <>

Frederic Tuong <>

Louis Gesbert <>

Vincent Bernardoff <>

Guillem Rieu <>

Roberto Di Cosmo <>


Check bug reports at

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Opam 1.2.2 OPAM-CONFIG (1)

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