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.