emerge

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emerge is the main command-line interface to Portage, the Gentoo package manager.

emerge is used to download, install, update, and maintain software packages on Gentoo Linux.

emerge is a very powerful and flexible command that can, among other things, automatically build and install packages "from source", fetch and install "ready-to-use" binary packages, create binary packages, search for packages, report system information, etc.

Tip
The emerge command has many possible options. For extensive documentation and a complete list of all options see man emerge.

See also

See the Portage article for Portage usage beyond the emerge command.

The working with Gentoo and working with Portage chapters of the handbook have sections on using the emerge command.

Some common questions about the emerge command are answered in the FAQ and in the Portage FAQ.

Usage

Invocation

The emerge command should be followed by appropriate options, actions, and package or set of packages. If emerge is invoked without any parameters or package, it will print a help text and exit.

For most uses emerge will need to be executed with superuser privileges, though when used simply to report information it may be possible to run it as an unprivileged user.

If emerge is invoked with a package and no other options, it will immediately attempt to install the corresponding package without requesting confirmation from the user. This is often not the desired behavior, so one of the following options will probably be required.

The --ask (-a) and --pretend (-p) options allow examination of the planned system changes before they are actually made. The --ask option will make emerge display the intended changes and ask for confirmation before continuing. The --pretend option will simply display the intended changes and halt, and does not require superuser privileges.

Warning
When using the --ask option, an accidental press of the Enter key during processing will result in the confirmation prompt being skipped. See the --ask option section of man emerge for more information.

emerge provides rich output, with information and warnings about individual packages and the system as a whole. The --verbose option is useful to have Portage show even more information, such as what USE flags will be used to install or update a package, what USE flags are available for each package, the size of the package download, etc.

Running emerge with the --help option provides information on command line options:

user $emerge --help

emerge: command-line interface to the Portage system
Usage:
   emerge [ options ] [ action ] [ ebuild | tbz2 | file | @set | atom ] [ ... ]
   emerge [ options ] [ action ] < @system | @world >
   emerge < --sync | --metadata | --info >
   emerge --resume [ --pretend | --ask | --skipfirst ]
   emerge --help
Options: -[abBcCdDefgGhjkKlnNoOpPqrsStuUvVwW]
          [ --color < y | n >            ] [ --columns    ]
          [ --complete-graph             ] [ --deep       ]
          [ --jobs JOBS ] [ --keep-going ] [ --load-average LOAD            ]
          [ --newrepo   ] [ --newuse     ] [ --noconfmem  ] [ --nospinner   ]
          [ --oneshot   ] [ --onlydeps   ] [ --quiet-build [ y | n ]        ]
          [ --reinstall changed-use      ] [ --with-bdeps < y | n >         ]
Actions:  [ --depclean | --list-sets | --search | --sync | --version        ]
 
 
For more help consult the man page.

Below is an example invocation of emerge, installing "package". The options -atv are short options for --ask (see above), --tree (display the dependency tree of packages to be installed), and --verbose (see above). Hover the mouse cursor over the red dotted boxes to see an explanation of each section of output:

# emerge -atv package
These are the packages that would be merged, in reverse order:
Calculating dependencies... done!
[ebuild     U  ] category/package-3.0-r2 [2.0] USE="enabled -disabled toggled* new% (-unavailable)" MAKE_OPTIONS="-disabled" 777 kB
[ebuild     UD ]  category/package-2.0 [3.0] 777 kB
[ebuild   R    ]   category/package-1.0  777 kB
[ebuild  N     ]  category/package-0.5  777 kB
Total: 4 packages (1 new, 1 reinstall, 1 upgrade, 1 downgrade), Size of downloads: 3108 kB
Would you like to merge these packages? [Yes/No]

The U symbol shows a package that will be upgraded, D a package that will be downgraded, R re-emerged, N a new package. In square brackets is the version of the previously installed package. Packages present in the world file are shown in bold - these are the user-installed packages, the other packages will be dependencies, or from the system set.

See also
See the OUTPUT section, and --pretend option, of the emerge man page for complete explanation of how to read Portage output.

In the context of Portage, the term "package" can have a similar meaning to "atom", see version specifier.

Install a package

Install the net-proxy/tinyproxy package with --ask and --verbose options:

root #emerge --ask --verbose net-proxy/tinyproxy

What package, version, and slot, to install, and from which ebuild repository is indicated using a version specifier.

Tip
The --ask (-a) option is very useful, it will allow the emerge actions to be reviewed before the actual operation begins. The --verbose (-v) option will show more detailed information about what Portage will do, and is often helpful. Options can be set as default, if desired. Default options can be overridden on the command line, for example --ask=n.

Warning
If the --ask option is not provided, requested actions will be performed without ever asking for confirmation. The --pretend option may also be used.

Note
Some things, such as dependencies, should not be installed in this way. See do not add dependencies to the world file section.

Package functionality is governed at install time by USE flags which can be set or unset depending on the intended use of a piece of software.

Search for packages

Note
The emerge command's built-in search function described here may show limited results compared to other tools. The Latest version available is constrained by ACCEPT_KEYWORDS (derived from the current profile, make.conf, package.accept_keywords, etc.). In addition, the Latest version available and the Latest installed version are not slot-aware, so they will not show multiple versions by slot. This can lead to some confusion when tools like eix or eshowkw might show more results than emerge --search.

See also
See also eix, equery, and packages.gentoo.org for more advanced ways to search for packages.

Search for packages with proxy in their names:

user $emerge --search proxy

Search for packages with proxy in their names or description:

user $emerge --searchdesc proxy

Search packages using a regular expression:

user $emerge -s '%^python$'

List all packages in a category:

user $emerge -s '@net-ftp'

Remove (uninstall) packages

Remove the net-proxy/tinyproxy package using the dependency sensitive --depclean (-c) option:

root #emerge --ask --verbose --depclean net-proxy/tinyproxy

This should only remove packages that are not needed as a dependency of a currently installed package.

An alternative to using --depclean to uninstall packages, is to use emerge --deselect (or -W option), then cleaning out orphaned packages, as described in the following section.

Note
Do not confuse the lower case -c switch, which is short for --depclean (and is safe), with the upper case -C switch which risks damaging the system and should only be used when absolutely required (see warning below).

Warning
Do not use the --unmerge (-C) option (unless its particular behavior is known to be specifically required). This option will remove important packages that are needed for the system to function, without warning.

Cleaning out orphaned packages

See also
See remove orphaned packages for information on how to use emerge --depclean to remove potentially unused packages. See also the Portage FAQ.

Update packages

See Upgrading Gentoo for how to update packages.

Get system information

emerge can print system information that can be useful for troubleshooting. This information is often required to be posted when asking for support, or when filing a bug.

user $emerge --info

Extra information may be output by using the --verbose flag.

Tips

Verifying and (re)downloading distfiles

To re-verify the integrity of and re-download previously removed/corrupted distfiles for all currently installed packages, run:

root #emerge --ask --fetchonly --emptytree @world

Do not add dependencies to the world file

If a dependency must be reinstalled, use the --oneshot option. Installing dependencies with the emerge package command would add them to the world file and may lead to issues.

Installing dependencies with Portage for compiling custom source software is also ill advised: it is preferable to write an ebuild.

See also
See User:Sam/Portage help/Maintaining a Gentoo_system for more information.

Resume emerge

If an emerge of several packages is interrupted (e.g. ctrl+c, crash...), the emerge may be resumed from the failed package with the --resume option. The --keep-going and --skipfirst options may also be of interest. See the emerge man page for details.

Passing temporary configuration to Portage through environment variables

Warning
Passing environment variables to Portage on the command line will only result in temporary changes to system configuration, and all such changes will be reverted by routine maintenance, such as a system update. Though this section can be useful for previewing the effects of configuration changes, with the --pretend option, it should not be used when actually installing or updating packages.

The correct way to make Portage configuration changes is through the Portage configuration files such as /etc/portage/make.conf, /etc/portage/package.accept_keywords, /etc/portage/package.use, etc.

The emerge command can be passed temporary configuration values by declaring environment variables on the command line, in order to affect behavior for that invocation alone. For example, to merge app-editors/emacs with the svg USE flag enabled, but not make this USE flag setting permanent:

root #USE='svg' emerge app-editors/emacs

Or to pass extra configuration options to packages that use the econf function in their ebuild:

root #EXTRA_ECONF='--without-compress-install' emerge app-editors/emacs

Note
If using sudo to invoke emerge, environment variables may need to be set after the sudo invocation, as sudo won't usually preserve the environment from which it is run:

user $sudo USE='svg' emerge -av app-editors/emacs

re-emerging a package that provided a specific File

Sometimes it is useful to be able to re-emerge a package simply by specifying a particular file that was provided by that package.

As an example, if the user wants to reinstall /usr/lib/libunwind.a but it is not known which package provided this file, the package from where that file came can be determined by emerge by simply indicating the file path:

user $emerge -p /usr/lib/libunwind.a

These are the packages that would be merged, in order:
 
Calculating dependencies... done!
Dependency resolution took 2.76 s (backtrack: 0/20).
 
[ebuild   R    ] sys-libs/llvm-libunwind-17.0.6

Only files that have been provided by a currently-installed package may be re-emerged in this way. See Pfl for other ways to find what packages files might "belong" to.

Troubleshooting

See also
See User:Sam/Portage help for topics on Portage issues.

Emerging packages fail during 'unpack' stage

The following message can occur when emerging packages:

 * Error messages for package dev-libs/libinput-1.16.0:
 * The ebuild phase 'unpack' has exited unexpectedly. This type of behavior
 * is known to be triggered by things such as failed variable assignments
 * (bug #190128) or bad substitution errors (bug #200313). Normally, before
 * exiting, bash should have displayed an error message above. If bash did
 * not produce an error message above, it's possible that the ebuild has
 * called `exit` when it should have called `die` instead. This behavior
 * may also be triggered by a corrupt bash binary or a hardware problem
 * such as memory or cpu malfunction. If the problem is not reproducible or
 * it appears to occur randomly, then it is likely to be triggered by a
 * hardware problem. If you suspect a hardware problem then you should try
 * some basic hardware diagnostics such as memtest. Please do not report
 * this as a bug unless it is consistently reproducible and you are sure
 * that your bash binary and hardware are functioning properly.

Although this issue may be due to the reasons listed in the output above, it can often be caused by low disk space in the path used by Portage to unpack the ebuild's source files. This location is set via the PORTAGE_TMPDIR variable and can be quickly found by querying Portage:

user $portageq envvar PORTAGE_TMPDIR

/var/tmp

The df command may be used to view available disk space for the partition where PORTAGE_TMPDIR has been mounted (this will likely be the root (/) partition). See Freeing disk space for details on how to free up disk space.