Provided by: opam-doc_2.0.5-1ubuntu1_all 
NAME
opam-switch - Manage multiple installation prefixes.
SYNOPSIS
opam switch [OPTION]... [COMMAND] [ARG]...
DESCRIPTION
This command is used to manage "switches", which are independent installation prefixes with their own
compiler and sets of installed and pinned packages. This is typically useful to have different versions
of the compiler available at once.
Use opam switch create to create a new switch, and opam switch set to set the currently active switch.
Without argument, lists installed switches, with one switch argument, defaults to set.
Switch handles SWITCH can be either a plain name, for switches that will be held inside ~/.opam, or a
directory name, which in that case is the directory where the switch prefix will be installed, as _opam.
Opam will automatically select a switch by that name found in the current directory or its parents,
unless OPAMSWITCH is set or --switch is specified. When creating a directory switch, if package
definitions are found locally, the user is automatically prompted to install them after the switch is
created unless --no-install is specified.
opam switch set sets the default switch globally, but it is also possible to select a switch in a given
shell session, using the environment. For that, use eval $(opam env --switch=SWITCH --set-switch).
COMMANDS
Without argument, defaults to list.
SWITCH
With a SWITCH argument, defaults to set SWITCH.
create SWITCH [COMPILER]
Create a new switch, and install the given compiler there. SWITCH can be a plain name, or a
directory, absolute or relative, in which case a local switch is created below the given directory.
COMPILER, if omitted, defaults to SWITCH if it is a plain name, unless --packages or --empty is
specified. When creating a local switch, and none of these options are present, the compiler is
chosen according to the configuration default (see opam-init(1)). If the chosen directory contains
package definitions, a compatible compiler is searched within the default selection, and the packages
will automatically get installed.
set SWITCH
Set the currently active switch, among the installed switches.
remove SWITCH
Remove the given switch from disk.
export FILE
Save the current switch state to a file. If --full is specified, it includes the metadata of all
installed packages
import FILE
Import a saved switch state. If --switch is specified and doesn't point to an existing switch, the
switch will be created for the import.
reinstall [SWITCH]
Reinstall the given compiler switch and all its packages.
list
Lists installed switches.
list-available [PATTERN]
Lists base packages that can be used to create a new switch, i.e. packages with the compiler flag
set. If no pattern is supplied, all versions are shown.
show
Prints the name of the current switch.
set-base PACKAGES
Sets the packages forming the immutable base for the selected switch, overriding the current setting.
set-description STRING
Sets the description for the selected switch
link SWITCH [DIR]
Sets a local alias for a given switch, so that the switch gets automatically selected whenever in
that directory or a descendant.
install SWITCH
Deprecated alias for 'create'.
OPTIONS
-A COMP, --alias-of=COMP
This option is deprecated.
--deps-only
When creating a local switch in a project directory (i.e. a directory containing opam package
definitions), install the dependencies of the project but not the project itself.
--description=STRING
Attach the given description to a switch when creating it. Use the set-description subcommand to
modify the description of an existing switch.
--empty
Allow creating an empty (without compiler) switch.
--full
When exporting, include the metadata of all installed packages, allowing to re-import even if they
don't exist in the repositories (the default is to include only the metadata of pinned packages).
-j JOBS, --jobs=JOBS
Set the maximal number of concurrent jobs to use. The default value is calculated from the number of
cores. You can also set it using the $OPAMJOBS environment variable.
--no-autoinstall
This option is deprecated.
--no-install
When creating a local switch, don't look for any local package definitions to install.
--no-switch
Don't automatically select newly installed switches.
--packages=PACKAGES
When installing a switch, explicitly define the set of packages to set as the compiler.
--repositories=REPOS
When creating a new switch, use the given selection of repositories instead of the default. REPOS
should be a comma-separated list of either already registered repository names (configured through
e.g. opam repository add --dont-select), or NAME=URL bindings, in which case NAME should not be
registered already to a different URL, and the new repository will be registered. See opam repository
for more details. This option also affects list-available.
-s, --short
Output raw lists of names, one per line, skipping any details.
PACKAGE BUILD OPTIONS
-b, --keep-build-dir
Keep the build directories after compiling packages. This is equivalent to setting $OPAMKEEPBUILDDIR
to "true".
-d, --with-doc, --build-doc
Build the package documentation. This only affects packages listed on the command-line. The
--build-doc form is deprecated as this does also installation. This is equivalent to setting
$OPAMWITHDOC (or the deprecated $OPAMBUILDDOC) to "true".
--dry-run
Simulate the command, but don't actually perform any changes. This also can be set with environment
variable $OPAMDEBUG.
--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.
--ignore-constraints-on[=PACKAGES] (default=)
Forces opam to ignore version constraints on all dependencies to the listed packages. This can be
used to test compatibility, but expect builds to break when using this. Note that version constraints
on optional dependencies and conflicts are unaffected. This is equivalent to setting
$OPAMIGNORECONSTRAINTS.
--inplace-build
When compiling a package which has its source bound to a local directory, process the build and
install actions directly in that directory, rather than in a clean copy handled by opam. This only
affects packages that are explicitly listed on the command-line. This is equivalent to setting
$OPAMINPLACEBUILD to "true".
--locked[=SUFFIX] (default=locked)
In commands that use opam files found from pinned sources, if a variant of the file with an added
.SUFFIX extension is found (e.g. foo.opam.locked besides foo.opam), that will be used instead. This
is typically useful to offer a more specific set of dependencies and reproduce similar build
contexts, hence the name. The opam lock plugin can be used to generate such files, based on the
versions of the dependencies currently installed on the host. This is equivalent to setting the
$OPAMLOCKED environment variable. Note that this option doesn't generally affect already pinned
packages.
-m MAKE, --make=MAKE
Use MAKE as the default 'make' command. Deprecated: use opam config set[-global] make MAKE instead.
Has no effect if the make variable is defined.
--no-checksums
Do not verify the checksum of downloaded archives.This is equivalent to setting $OPAMNOCHECKSUMS to
"true".
--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".
--reuse-build-dir
Reuse existing build directories (kept by using --keep-build-dir), instead of compiling from a fresh
clone of the source. This can be faster, but also lead to failures if the build systems of the
packages don't handle upgrades of dependencies well. This is equivalent to setting $OPAMREUSEBUILDDIR
to "true".
--show-actions
Call the solver and display the actions. Don't perform any changes. This is equivalent to setting
$OPAMSHOW.
--skip-updates
When running an install, upgrade or reinstall on source-pinned packages, they are normally updated
from their origin first. This flag disables that behaviour and will keep them to their version in
cache. This is equivalent to setting $OPAMSKIPUPDATE.
-t, --with-test, --build-test
Build and run the package unit-tests. This only affects packages listed on the command-line. The
--build-test form is deprecated as this also affects installation. This is equivalent to setting
$OPAMWITHTEST (or the deprecated $OPAMBUILDTEST) to "true".
--unlock-base
Allow changes to the packages set as switch base (typically, the main compiler). Use with caution.
This is equivalent to setting the $OPAMUNLOCKBASE environment variable
COMMON OPTIONS
These options are common to all commands.
--best-effort
Don't fail if all requested packages can't be installed: try to install as many as possible. Note
that not all external solvers may support this option (recent versions of aspcud or mccs should).
This is equivalent to setting $OPAMBESTEFFORT environment variable.
--color=WHEN
Colorize the output. WHEN must be one of `always', `never' or `auto'.
--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/External_solvers.html. A general guide to using solver preferences can be
found at http://www.dicosmo.org/Articles/usercriteria.pdf.
--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 of opam, if set (i.e. you are using a development version), and exit.
--help[=FMT] (default=auto)
Show this help in format FMT. The value FMT must be one of `auto', `pager', `groff' or `plain'. With
`auto', the format is `pager` or `plain' whenever the TERM env var is `dumb' or undefined.
--ignore-pin-depends
Ignore extra pins required by packages that get pinned, either manually through opam pin or through
opam install DIR. This is equivalent to setting IGNOREPINDEPENDS=true.
--json=FILENAME
Save the results of the opam run in a computer-readable file. If the filename contains the character
`%', it will be replaced by an index that doesn't overwrite an existing file. Similar to setting the
$OPAMJSON variable.
--no-aspcud
Deprecated.
--no-auto-upgrade
When configuring or updating a repository that is written for an earlier opam version (1.2), opam
internally converts it to the current format. This disables this behaviour. Note that repositories
should define their format version in a 'repo' file at their root, or they will be assumed to be in
the older format. It is, in any case, preferable to upgrade the repositories manually using opam
admin upgrade [--mirror URL] when possible.
--no-self-upgrade
Opam will replace itself with a newer binary found at OPAMROOT/opam if present. This disables this
behaviour.
-q, --quiet
Disables --verbose.
--root=ROOT
Use ROOT as the current root path. This is equivalent to setting $OPAMROOT to ROOT.
--safe, --readonly
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. This is equivalent to set
environment variable $OPAMSAFE.
--solver=CMD
Specify the CUDF solver to use for resolving package installation problems. This is either a
predefined solver (this version of opam supports builtin-mccs+lp(), builtin-mccs+glpk, aspcud, mccs,
aspcud-old, packup), or a custom command that should contain the variables %{input}%, %{output}%,
%{criteria}%, and optionally %{timeout}%. This is equivalent to setting $OPAMEXTERNALSOLVER.
--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
Disable any external solver, and use the built-in one (this requires that opam has been compiled with
a built-in solver). This is equivalent to setting $OPAMNOASPCUD or $OPAMUSEINTERNALSOLVER.
-v, --verbose
Be more verbose. One -v shows all package commands, repeat to also display commands called internally
(e.g. tar, curl, patch etc.) Repeating n times is equivalent to setting $OPAMVERBOSE to "n".
--version
Show version information.
-w, --working-dir
Whenever updating packages that are bound to a local, version-controlled directory, update to the
current working state of their source instead of the last committed state, or the ref they are
pointing to. This only affects packages explicitly listed on the command-line.It can also be set with
$OPAMWORKINGDIR.
-y, --yes
Answer yes to all yes/no questions without prompting. This is equivalent to setting $OPAMYES to
"true".
ENVIRONMENT VARIABLES
Opam makes use of the environment variables listed here. Boolean variables should be set to "0", "no",
"false" or the empty string to disable, "1", "yes" or "true" to enable.
OPAMALLPARENS surround all filters with parenthesis
OPAMAUTOREMOVE see remove option `--auto-remove`
OPAMBESTEFFORT see option `--best-effort`
OPAMBESTEFFORTPREFIXCRITERIA sets the string that must be prepended to the criteria when the
`--best-effort` option is set, and is expected to maximise the `opam-query` property in the solution
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 depends on the solver
version, use `config report` to know the current setting. See also option --criteria
OPAMCUDFFILE file save the cudf graph to file-actions-explicit.dot
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.
OPAMDRYRUN see option `--dry-run`
OPAMEDITOR sets the editor to use for opam file editing, overrides $EDITOR and $VISUAL
OPAMERRLOGLEN sets the number of log lines printed when a sub-process fails. 0 to print all.
OPAMEXTERNALSOLVER see option `--solver'.
OPAMFAKE see option `--fake`
OPAMFETCH specifies how to download files: either `wget', `curl' or a custom command where variables
%{url}%, %{out}%, %{retry}%, %{compress}% and %{checksum}% will be replaced. Overrides the
'download-command' value from the main config file.
OPAMFIXUPCRITERIA same as OPAMUPGRADECRITERIA, but specific to fixup
OPAMIGNORECONSTRAINTS see install option `--ignore-constraints-on`
OPAMIGNOREPINDEPENDS see option `--ignore-pin-depends`
OPAMJOBS sets the maximum number of parallel workers to run.
OPAMJSON log json output to the given file (use character `%' to index the files)
OPAMLOCKED see install option `--locked`
OPAMLOGS logdir sets log directory, default is a temporary directory in /tmp
OPAMMAKECMD set the system make command to use
OPAMNOAUTOUPGRADE disables automatic internal upgrade of repositories in an earlier format to the current
one, on 'update' or 'init'.
OPAMKEEPLOGS tells opam to not remove some temporary command logs and some backups. This skips some
finalisers and may also help to get more reliable backtraces
OPAMLOCKRETRIES sets the number of tries after which opam gives up acquiring its lock and fails. <= 0
means infinite wait.
OPAMMERGEOUT merge process outputs, stderr on stdout
OPAMNO answer no to any question asked.
OPAMNOASPCUD Deprecated.
OPAMNOCHECKSUMS enables option --no-checksums when available.
OPAMNOSELFUPGRADE see option `--no-self-upgrade'.
OPAMPINKINDAUTO sets whether version control systems should be detected when pinning to a local path.
Enabled by default since 1.3.0.
OPAMPRECISETRACKING fine grain tracking of directories
OPAMREQUIRECHECKSUMS Enables option `--require-checksums' when available (e.g. for `opam install`).
OPAMRETRES sets the number of tries before failing downloads.
OPAMROOT see option `--root'. This is automatically set by `opam env --root=DIR --set-root'.
OPAMROOTISOK don't complain when running as root.
OPAMSAFE see option `--safe'
OPAMSHOW see option `--show`
OPAMSKIPUPDATE see option `--skip-updates`
OPAMSKIPVERSIONCHECKS bypasses some version checks. Unsafe, for compatibility testing only.
OPAMSOLVERTIMEOUT change the time allowance of the solver. Default is 60.0, set to 0 for unlimited. Note
that all solvers may not support this option.
OPAMSTATUSLINE display a dynamic status line showing what's currently going on on the terminal. (one of
one of `always', `never' or `auto')
OPAMSTATS display stats at the end of command
OPAMSTRICT fail on inconsistencies (file reading, switch import, etc.)
OPAMSWITCH see option `--switch'. Automatically set by `opam env --switch=SWITCH --set-switch'.
OPAMUNLOCKBASE see install option `--unlock-base`
OPAMUPGRADECRITERIA specifies user preferences for dependency solving when performing an upgrade.
Overrides OPAMCRITERIA in upgrades if both are set. See also option --criteria
OPAMUSEINTERNALSOLVER see option `--use-internal-solver'.
OPAMUSEOPENSSL force openssl use for hash computing
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.
OPAMVALIDATIONHOOK hook if set, uses the `%{hook%}` command to validate an opam repository update
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'.
OPAMWORKINGDIR see option `--working-dir`
OPAMYES see option `--yes'.
EXIT STATUS
As an exception to the following, the `exec' command returns 127 if the command was not found or couldn't
be executed, and the command's exit value otherwise.
0 Success, or true for boolean queries.
1 False. Returned when a boolean return value is expected, e.g. when running with --check, or for
queries like opam lint.
2 Bad command-line arguments, or command-line arguments pointing to an invalid context (e.g. file not
following the expected format).
5 Not found. You requested something (package, version, repository, etc.) that couldn't be found.
10 Aborted. The operation required confirmation, which wasn't given.
15 Could not acquire the locks required for the operation.
20 There is no solution to the user request. This can be caused by asking to install two incompatible
packages, for example.
30 Error in package definition, or other metadata files. Using --strict raises this error more often.
31 Package script error. Some package operations were unsuccessful. This may be an error in the packages
or an incompatibility with your system. This can be a partial error.
40 Sync error. Could not fetch some remotes from the network. This can be a partial error.
50 Configuration error. Opam or system configuration doesn't allow operation, and needs fixing.
60 Solver failure. The solver failed to return a sound answer. It can be due to a broken external
solver, or an error in solver configuration.
99 Internal error. Something went wrong, likely due to a bug in opam itself.
130 User interrupt. SIGINT was received, generally due to the user pressing Ctrl-C.
FURTHER DOCUMENTATION
See https://opam.ocaml.org/doc.
AUTHORS
Vincent Bernardoff <vb@luminar.eu.org>
Raja Boujbel <raja.boujbel@ocamlpro.com>
Roberto Di Cosmo <roberto@dicosmo.org>
Thomas Gazagnaire <thomas@gazagnaire.org>
Louis Gesbert <louis.gesbert@ocamlpro.com>
Fabrice Le Fessant <Fabrice.Le_fessant@inria.fr>
Anil Madhavapeddy <anil@recoil.org>
Guillem Rieu <guillem.rieu@ocamlpro.com>
Ralf Treinen <ralf.treinen@pps.jussieu.fr>
Frederic Tuong <tuong@users.gforge.inria.fr>
BUGS
Check bug reports at https://github.com/ocaml/opam/issues.
Opam 2.0.5 OPAM-SWITCH(1)