SYNOPSIS

opam switch [OPTION]... [COMMAND] [ARG]...

DESCRIPTION

This command allows one to switch between different compiler versions, installing the compiler if opam switch is used to switch to that compiler for the first time. The different compiler versions are totally independent from each other, meaning that OPAM maintains a separate state (e.g. list of installed packages...) for each.

See the documentation of opam switch list to see the compilers which are available, and how to switch or to install a new one.

COMMANDS

Without argument, defaults to list.

SWITCH

With a SWITCH argument, defaults to set SWITCH.

install SWITCH

Install the given compiler. The command fails if the switch is already installed (e.g. it will not transparently switch to the installed compiler switch, as with set).

set SWITCH

Set the currently active switch, installing it if needed.

remove SWITCH

Remove the given compiler.

export FILE

Save the current switch state to a file.

import FILE

Import a saved switch state.

reinstall SWITCH

Reinstall the given compiler switch. This will also reinstall all packages.

list

List compilers. By default, lists installed and `standard' compilers. Use `--all' to get the list of all installable compilers. The first column displays the switch name (if any), the second one the switch state (C = current, I = installed, -- = not installed), the third one the compiler name and the last one the compiler description. To switch to an already installed compiler alias (with state = I), use opam switch <name>. If you want to use a new compiler <comp>, use opam switch <comp>: this will download, compile and create a fresh and independent environment where new packages can be installed. If you want to create a new compiler alias (for instance because you already have this compiler version installed), use opam switch <name> --alias-of <comp>. In case <name> and <comp> are the same, this is equivalent to opam switch <comp>.

show

Show the current compiler.

OPTIONS

-A COMP, --alias-of=COMP

The name of the compiler description which will be aliased.

-a, --all

List all the compilers which can be installed on the system.

-b, --keep-build-dir

Keep the build directory. This is equivalent to setting $OPAMKEEPBUILDDIR to "true".

-d, --build-doc

Build the package documentation. This is equivalent to setting $OPAMBUILDDOC to "true".

--dry-run

Simulate the command, but don't actually perform any changes.

-e TAGS, --external=TAGS

Display the external packages associated to the given tags.

--fake

This option registers the actions into the OPAM database, without actually performing them. WARNING: This option is dangerous and likely to break your OPAM environment. You probably want `--dry-run'. You've been warned.

-i, --installed

List installed compiler switches only.

-j JOBS, --jobs=JOBS

Set the maximal number of concurrent jobs to use. You can also set it using the $OPAMJOBS environment variable.

--json=FILENAME

Save the result output of an OPAM run in a computer-readable file

-m MAKE, --make=MAKE

Use MAKE as the default 'make' command.

--no-checksums

Do not verify the checksum of downloaded archives.This is equivalent to setting $OPAMNOCHECKSUMS to "true".

--no-switch

Only install the compiler switch, without switching to it. If the compiler switch is already installed, then do nothing.

--no-warning

Do not display any warning related to environment variables.

--require-checksums

Reject the installation of packages that don't provide a checksum for the upstream archives. This is equivalent to setting $OPAMREQUIRECHECKSUMS to "true".

-s, --short

Output the names separated by one whitespace instead of using the usual formatting.

--show-actions

Call the solver and display the actions. Don't perform any changes.

-t, --build-test

Build and run the package unit-tests. This is equivalent to setting $OPAMBUILDTEST to "true".

COMMON OPTIONS

These options are common to all commands.

--color=WHEN (absent=auto)

Colorize the output. WHEN must be `always', `never' or `auto'.

--compat-mode-1.0

Compatibility mode with OPAM 1.0

--criteria=CRITERIA

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.

--cudf=FILENAME

Debug option: Save the CUDF requests sent to the solver to FILENAME-<n>.cudf.

--debug

Print debug message to stderr. This is equivalent to setting $OPAMDEBUG to "true".

--debug-level=LEVEL

Like `--debug', but allows specifying the debug level (`--debug' sets it to 1). Equivalent to setting $OPAMDEBUG to a positive integer.

--git-version

Print the git version if it exists and exit.

--help[=FMT] (default=pager)

Show this help in format FMT (pager, plain or groff).

--no-base-packages

Do not install base packages (useful for testing purposes). This is equivalent to setting $OPAMNOBASEPACKAGES to a non-empty string.

--no-self-upgrade

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.

--safe

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.

--solver=CMD

Specify the name of the external dependency solver. The default value is aspcud

--strict

Fail whenever an error is found in a package definition or a configuration file. The default is to continue silently if possible.

--switch=SWITCH

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".

--version

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".

FURTHER DOCUMENTATION

See https://opam.ocaml.org.

AUTHORS

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]>