opam install --help

NAME
       opam-install - Install a list of packages.

SYNOPSIS
       opam install [OPTION]... PACKAGES...

DESCRIPTION
       This command installs one or more packages to the currently selected
       compiler. To install packages for another compiler, you need to switch
       compilers using opam switch. You can remove installed packages with
       opam remove, and list installed packages with opam list -i. See opam
       pin as well to understand how to manage package versions.

       This command makes OPAM use the dependency solver to compute the
       transitive closure of dependencies to be installed, and will also
       handle conflicts. If the dependency solver returns more than one
       solution, OPAM will arbitrarily select the first one. If dependencies
       are to be installed, OPAM will confirm if the installation should
       proceed.

ARGUMENTS
       PACKAGES
           List of package names, with an optional version or constraint, e.g
           `pkg', `pkg.1.0' or `pkg>=0.5'.

OPTIONS
       -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".

       --deps-only
           Install all its dependencies, but don't actually install the
           package.

       --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. This
           is deprecated, use `opam list --external' instead

       --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.

       -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".

       --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".

       --set-root
           Mark given packages as installed roots. This is the default for
           newly manually-installed packages.

       --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".

       --unset-root
           Mark given packages as "installed automatically".

COMMON OPTIONS
       These options are common to all commands.

       --color=WHEN (absent=auto)
           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/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),-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.

       --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. Either 'aspcud', 'packup' or a custom command
           that may contain the variables %{input}%, %{output}% and
           %{criteria}%

       --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 package sub-commands and their output.
           Repeat to see more. Repeating n times is equivalent to setting
           $OPAMVERBOSE to "n".

       --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".

ENVIRONMENT VARIABLES
       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'.

FURTHER DOCUMENTATION
       See https://opam.ocaml.org.

AUTHORS
       Thomas Gazagnaire <thomas@gazagnaire.org>
       Anil Madhavapeddy <anil@recoil.org>
       Fabrice Le Fessant <Fabrice.Le_fessant@inria.fr>
       Frederic Tuong <tuong@users.gforge.inria.fr>
       Louis Gesbert <louis.gesbert@ocamlpro.com>
       Vincent Bernardoff <vb@luminar.eu.org>
       Guillem Rieu <guillem.rieu@ocamlpro.com>
       Roberto Di Cosmo <roberto@dicosmo.org>

BUGS
       Check bug reports at https://github.com/ocaml/opam/issues.