emerge

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emerge is the command-line interface to Portage and is how most users will interact with Portage. It is one of the most important commands on Gentoo.

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

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.

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

Usage

Invocation

emerge can provide rich output about what changes will be made, and will provide information and warnings about individual packages or the system. The --ask, --pretend, and --verbose options are useful to have Portage show more information - by default, the emerge command will perform the requested action immediately.

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, --tree, and --verbose. They trigger emerge to ask before proceeding, display the dependency tree of packages to be installed, and to be verbose with its 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 also be referred to as an "atom", the terms can be used interchangeably. 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.

Tip
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 the system. Any such changes will be reverted by system updates. This method will mainly be useful for previewing the effects of configuration changes, with the --pretend option. Changes to Portage configuration are normally made through the 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

Emerging a File

Sometimes it is useful to directly emerge a file, an example of this is if a package needs /usr/lib/libunwind.a but it is unknown which package provides this file.

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

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 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.