nix-env - manipulate or query Nix user environments
nix-env [
--help] [
--version]
[{
--verbose |
-v}...] [
--quiet]
[
--no-build-output |
-Q]
[{
--max-jobs |
-j}
number]
[
--cores number]
[
--max-silent-time number] [
--timeout number] [
--keep-going |
-k]
[
--keep-failed |
-K] [
--fallback]
[
--readonly-mode] [
-I path]
[
--option name value]
[
--arg name value]
[
--argstr name value]
[{
--file |
-f}
path]
[{
--profile |
-p}
path]
[
--system-filter system] [
--dry-run]
operation [
options...] [
arguments...]
The command
nix-env is used to manipulate Nix user environments. User
environments are sets of software packages available to a user at some point
in time. In other words, they are a synthesised view of the programs available
in the Nix store. There may be many user environments: different users can
have different environments, and individual users can switch between different
environments.
nix-env takes exactly one
operation flag which indicates the
subcommand to be performed. These are documented below.
Several commands, such as
nix-env -q and
nix-env -i, take a list
of arguments that specify the packages on which to operate. These are extended
regular expressions that must match the entire name of the package. (For
details on regular expressions, see
regex(7).) The match is
case-sensitive. The regular expression can optionally be followed by a dash
and a version number; if omitted, any version of the package will match. Here
are some examples:
firefox
Matches the package name firefox and any version.
firefox-32.0
Matches the package name firefox and version 32.0.
gtk\\+
Matches the package name gtk+. The + character must be
escaped using a backslash to prevent it from being interpreted as a
quantifier, and the backslash must be escaped in turn with another backslash
to ensure that the shell passes it on.
.\*
Matches any package name. This is the default for most
commands.
'.*zip.*'
Matches any package name containing the string zip. Note
the dots: '*zip*' does not work, because in a regular expression, the
character * is interpreted as a quantifier.
'.*(firefox|chromium).*'
Matches any package name containing the strings firefox
or chromium.
This section lists the options that are common to all operations. These options
are allowed for every subcommand, though they may not always have an effect.
--file /
-f path
Specifies the Nix expression (designated below as the
active Nix expression) used by the
--install,
--upgrade,
and
--query --available operations to obtain derivations. The default
is ~/.nix-defexpr.
If the argument starts with http:// or https://, it is interpreted as the URL of
a tarball that will be downloaded and unpacked to a temporary location. The
tarball must include a single top-level directory containing at least a file
named default.nix.
--profile /
-p path
Specifies the profile to be used by those operations that
operate on a profile (designated below as the active profile). A
profile is a sequence of user environments called generations, one of
which is the current generation.
--dry-run
For the
--install,
--upgrade,
--uninstall,
--switch-generation,
--delete-generations
and
--rollback operations, this flag will cause
nix-env to print
what
would be done if this flag had not been specified, without
actually doing it.
--dry-run also prints out which paths will be substituted (i.e.,
downloaded) and which paths will be built from source (because no substitute
is available).
--system-filter system
By default, operations such as --query --available
show derivations matching any platform. This option allows you to use
derivations for the specified platform system.
--help
Prints out a summary of the command syntax and
exits.
--version
Prints out the Nix version number on standard output and
exits.
--verbose /
-v
Increases the level of verbosity of diagnostic messages
printed on standard error. For each Nix operation, the information printed on
standard output is well-defined; any diagnostic information is printed on
standard error, never on standard output.
This option may be specified repeatedly. Currently, the following verbosity
levels exist:
0
“Errors only”: only print messages
explaining why the Nix invocation failed.
1
“Informational”: print useful
messages about what Nix is doing. This is the default.
2
“Talkative”: print more informational
messages.
3
“Chatty”: print even more informational
messages.
4
“Debug”: print debug information.
5
“Vomit”: print vast amounts of debug
information.
--quiet
Decreases the level of verbosity of diagnostic messages
printed on standard error. This is the inverse option to
-v /
--verbose.
This option may be specified repeatedly. See the previous verbosity levels
list.
--no-build-output /
-Q
By default, output written by builders to standard output
and standard error is echoed to the Nix command's standard error. This option
suppresses this behaviour. Note that the builder's standard output and error
are always written to a log file in prefix/nix/var/log/nix.
--max-jobs /
-j number
Sets the maximum number of build jobs that Nix will
perform in parallel to the specified number. Specify auto to use the number of
CPUs in the system. The default is specified by the max-jobs configuration
setting, which itself defaults to 1. A higher value is useful on SMP systems
or to exploit I/O latency.
--cores
Sets the value of the NIX_BUILD_CORES environment
variable in the invocation of builders. Builders can use this variable at
their discretion to control the maximum amount of parallelism. For instance,
in Nixpkgs, if the derivation attribute enableParallelBuilding is set
to true, the builder passes the -jN flag to GNU Make. It
defaults to the value of the cores configuration setting, if set, or 1
otherwise. The value 0 means that the builder should use all available CPU
cores in the system.
--max-silent-time
Sets the maximum number of seconds that a builder can go
without producing any data on standard output or standard error. The default
is specified by the max-silent-time configuration setting. 0 means no
time-out.
--timeout
Sets the maximum number of seconds that a builder can
run. The default is specified by the timeout configuration setting. 0 means no
timeout.
--keep-going /
-k
Keep going in case of failed builds, to the greatest
extent possible. That is, if building an input of some derivation fails, Nix
will still build the other inputs, but not the derivation itself. Without this
option, Nix stops if any build fails (except for builds of substitutes),
possibly killing builds in progress (in case of parallel or distributed
builds).
--keep-failed /
-K
Specifies that in case of a build failure, the temporary
directory (usually in /tmp) in which the build takes place should not be
deleted. The path of the build directory is printed as an informational
message.
--fallback
Whenever Nix attempts to build a derivation for which
substitutes are known for each output path, but realising the output paths
through the substitutes fails, fall back on building the derivation.
The most common scenario in which this is useful is when we have registered
substitutes in order to perform binary distribution from, say, a network
repository. If the repository is down, the realisation of the derivation will
fail. When this option is specified, Nix will build the derivation instead.
Thus, installation from binaries falls back on installation from source. This
option is not the default since it is generally not desirable for a transient
failure in obtaining the substitutes to lead to a full build from source (with
the related consumption of resources).
--no-build-hook
Disables the build hook mechanism. This allows to ignore
remote builders if they are setup on the machine.
It's useful in cases where the bandwidth between the client and the remote
builder is too low. In that case it can take more time to upload the sources
to the remote builder and fetch back the result than to do the computation
locally.
--readonly-mode
When this option is used, no attempt is made to open the
Nix database. Most Nix operations do need database access, so those operations
will fail.
--arg name value
This option is accepted by
nix-env,
nix-instantiate and
nix-build. When evaluating Nix expressions,
the expression evaluator will automatically try to call functions that it
encounters. It can automatically call functions for which every argument has a
default value (e.g., {
argName ?
defaultValue }:
...).
With
--arg, you can also call functions that have arguments without a
default value (or override a default value). That is, if the evaluator
encounters a function with an argument named
name, it will call it with
value
value.
For instance, the top-level default.nix in Nixpkgs is actually a function:
{ # The system (e.g., `i686-linux') for which to build the packages.
system ? builtins.currentSystem
...
}: ...
So if you call this Nix expression (e.g., when you do nix-env -i
pkgname), the function will be called automatically using the value
builtins.currentSystem for the system argument. You can override this using
--arg, e.g., nix-env -i
pkgname --arg system
\"i686-freebsd\". (Note that since the argument is a Nix string
literal, you have to escape the quotes.)
--argstr name value
This option is like --arg, only the value is not a
Nix expression but a string. So instead of --arg system
\"i686-linux\" (the outer quotes are to keep the shell happy) you
can say --argstr system i686-linux.
--attr /
-A attrPath
Select an attribute from the top-level Nix expression
being evaluated. (
nix-env,
nix-instantiate,
nix-build
and
nix-shell only.) The
attribute path attrPath is a
sequence of attribute names separated by dots. For instance, given a top-level
Nix expression
e, the attribute path xorg.xorgserver would cause the
expression
e.xorg.xorgserver to be used. See
nix-env --install
for some concrete examples.
In addition to attribute names, you can also specify array indices. For
instance, the attribute path foo.3.bar selects the bar attribute of the fourth
element of the array in the foo attribute of the top-level expression.
--expr /
-E
Interpret the command line arguments as a list of Nix
expressions to be parsed and evaluated, rather than as a list of file names of
Nix expressions. ( nix-instantiate, nix-build and
nix-shell only.)
-I path
Add a path to the Nix expression search path. This option
may be given multiple times. See the NIX_PATH environment variable for
information on the semantics of the Nix search path. Paths added through
-I take precedence over NIX_PATH.
--option name value
Set the Nix configuration option name to
value. This overrides settings in the Nix configuration file (see
nix.conf(5)).
--repair
Fix corrupted or missing store paths by redownloading or
rebuilding them. Note that this is slow because it requires computing a
cryptographic hash of the contents of every path in the closure of the build.
Also note the warning under nix-store --repair-path.
~/.nix-defexpr
A directory that contains the default Nix expressions
used by the
--install,
--upgrade, and
--query --available
operations to obtain derivations. The
--file option may be used to
override this default.
The Nix expressions in this directory are combined into a single set, with each
file as an attribute that has the name of the file. Thus, if ~/.nix-defexpr
contains two files, foo and bar, then the default Nix expression will
essentially be
{
foo = import ~/.nix-defexpr/foo;
bar = import ~/.nix-defexpr/bar;
}
The command
nix-channel places symlinks to the downloaded Nix expressions
from each subscribed channel in this directory.
~/.nix-profile
A symbolic link to the user's current profile. By
default, this symlink points to prefix/var/nix/profiles/default. The
PATH environment variable should include ~/.nix-profile/bin for the
user environment to be visible to the user.
nix-env {--install | -i}
[{--prebuilt-only | -b}]
[{--attr | -A}] [--from-expression]
[-E] [ --from-profile path]
[--preserve-installed | -P] [--remove-all | -r]
args...
The install operation creates a new user environment, based on the current
generation of the active profile, to which a set of store paths described by
args is added. The arguments
args map to store paths in a number
of possible ways:
•By default,
args is a set of derivation
names denoting derivations in the active Nix expression. These are realised,
and the resulting output paths are installed. Currently installed derivations
with a name equal to the name of a derivation being added are removed unless
the option
--preserve-installed is specified.
If there are multiple derivations matching a name in
args that have the
same name (e.g., gcc-3.3.6 and gcc-4.1.1), then the derivation with the
highest
priority is used. A derivation can define a priority by
declaring the
meta.priority attribute. This attribute should be a
number, with a higher value denoting a lower priority. The default priority is
0.
If there are multiple matching derivations with the same priority, then the
derivation with the highest version will be installed.
You can force the installation of multiple derivations with the same name by
being specific about the versions. For instance, nix-env -i gcc-3.3.6
gcc-4.1.1 will install both version of GCC (and will probably cause a user
environment conflict!).
•If --attr ( -A) is specified, the
arguments are attribute paths that select attributes from the top-level
Nix expression. This is faster than using derivation names and unambiguous. To
find out the attribute paths of available packages, use nix-env -qaP.
•If --from-profile path is given,
args is a set of names denoting installed store paths in the profile
path. This is an easy way to copy user environment elements from one
profile to another.
•If --from-expression is given, args
are Nix functions that are called with the active Nix expression as their
single argument. The derivations returned by those function calls are
installed. This allows derivations to be specified in an unambiguous way,
which is necessary if there are multiple derivations with the same name.
•If args are store derivations, then these
are realised, and the resulting output paths are installed.
•If args are store paths that are not store
derivations, then these are realised and installed.
•By default all outputs are installed for each
derivation. That can be reduced by setting meta.outputsToInstall.
--prebuilt-only /
-b
Use only derivations for which a substitute is
registered, i.e., there is a pre-built binary available that can be downloaded
in lieu of building the derivation. Thus, no packages will be built from
source.
--preserve-installed,
-P
Do not remove derivations with a name matching one of the
derivations being installed. Usually, trying to have two versions of the same
package installed in the same generation of a profile will lead to an error in
building the generation, due to file name clashes between the two versions.
However, this is not the case for all packages.
--remove-all,
-r
Remove all previously installed packages first. This is
equivalent to running nix-env -e '.*' first, except that everything happens in
a single transaction.
To install a specific version of
gcc from the active Nix expression:
$ nix-env --install gcc-3.3.2
installing `gcc-3.3.2'
uninstalling `gcc-3.1'
Note the previously installed version is removed, since
--preserve-installed was not specified.
To install an arbitrary version:
$ nix-env --install gcc
installing `gcc-3.3.2'
To install using a specific attribute:
$ nix-env -i -A gcc40mips
$ nix-env -i -A xorg.xorgserver
To install all derivations in the Nix expression foo.nix:
$ nix-env -f ~/foo.nix -i '.*'
To copy the store path with symbolic name gcc from another profile:
$ nix-env -i --from-profile /nix/var/nix/profiles/foo gcc
To install a specific store derivation (typically created by
nix-instantiate):
$ nix-env -i /nix/store/fibjb1bfbpm5mrsxc4mh2d8n37sxh91i-gcc-3.4.3.drv
To install a specific output path:
$ nix-env -i /nix/store/y3cgx0xj1p4iv9x0pnnmdhr8iyg741vk-gcc-3.4.3
To install from a Nix expression specified on the command-line:
$ nix-env -f ./foo.nix -i -E \
'f: (f {system = "i686-linux";}).subversionWithJava'
I.e., this evaluates to (f: (f {system =
"i686-linux";}).subversionWithJava) (import ./foo.nix), thus
selecting the subversionWithJava attribute from the set returned by calling
the function defined in ./foo.nix.
A dry-run tells you which paths will be downloaded or built from source:
$ nix-env -f '<nixpkgs>' -iA hello --dry-run
(dry run; not doing anything)
installing ‘hello-2.10’
these paths will be fetched (0.04 MiB download, 0.19 MiB unpacked):
/nix/store/wkhdf9jinag5750mqlax6z2zbwhqb76n-hello-2.10
...
To install Firefox from the latest revision in the Nixpkgs/NixOS 14.12 channel:
$ nix-env -f https://github.com/NixOS/nixpkgs-channels/archive/nixos-14.12.tar.gz -iA firefox
(The GitHub repository nixpkgs-channels is updated automatically from the main
nixpkgs repository after certain tests have succeeded and binaries have been
built and uploaded to the binary cache at cache.nixos.org.)
nix-env {--upgrade | -u}
[{--prebuilt-only | -b}]
[{--attr | -A}] [--from-expression]
[-E] [ --from-profile path] [--lt |
--leq | --eq | --always] args...
The upgrade operation creates a new user environment, based on the current
generation of the active profile, in which all store paths are replaced for
which there are newer versions in the set of paths described by
args.
Paths for which there are no newer versions are left untouched; this is not an
error. It is also not an error if an element of
args matches no
installed derivations.
For a description of how
args is mapped to a set of store paths, see
--install. If
args describes multiple store paths with the same
symbolic name, only the one with the highest version is installed.
--lt
Only upgrade a derivation to newer versions. This is the
default.
--leq
In addition to upgrading to newer versions, also
“upgrade” to derivations that have the same version. Version are
not a unique identification of a derivation, so there may be many derivations
that have the same version. This flag may be useful to force
“synchronisation” between the installed and available
derivations.
--eq
Only “upgrade” to derivations that
have the same version. This may not seem very useful, but it actually is,
e.g., when there is a new release of Nixpkgs and you want to replace installed
applications with the same versions built against newer dependencies (to
reduce the number of dependencies floating around on your system).
--always
In addition to upgrading to newer versions, also
“upgrade” to derivations that have the same or a lower version.
I.e., derivations may actually be downgraded depending on what is available in
the active Nix expression.
For the other flags, see
--install.
$ nix-env --upgrade gcc
upgrading `gcc-3.3.1' to `gcc-3.4'
$ nix-env -u gcc-3.3.2 --always (switch to a specific version)
upgrading `gcc-3.4' to `gcc-3.3.2'
$ nix-env --upgrade pan
(no upgrades available, so nothing happens)
$ nix-env -u (try to upgrade everything)
upgrading `hello-2.1.2' to `hello-2.1.3'
upgrading `mozilla-1.2' to `mozilla-1.4'
The upgrade operation determines whether a derivation
y is an upgrade of
a derivation
x by looking at their respective name attributes. The
names (e.g., gcc-3.3.1 are split into two parts: the package name (gcc), and
the version (3.3.1). The version part starts after the first dash not
following by a letter.
x is considered an upgrade of
y if their
package names match, and the version of
y is higher that that of
x.
The versions are compared by splitting them into contiguous components of
numbers and letters. E.g., 3.3.1pre5 is split into [3, 3, 1, "pre",
5]. These lists are then compared lexicographically (from left to right).
Corresponding components
a and
b are compared as follows. If
they are both numbers, integer comparison is used. If
a is an empty
string and
b is a number,
a is considered less than
b.
The special string component pre (for
pre-release) is considered to be
less than other components. String components are considered less than number
components. Otherwise, they are compared lexicographically (i.e., using
case-sensitive string comparison).
This is illustrated by the following examples:
1.0 < 2.3
2.1 < 2.3
2.3 = 2.3
2.5 > 2.3
3.1 > 2.3
2.3.1 > 2.3
2.3.1 > 2.3a
2.3pre1 < 2.3
2.3pre3 < 2.3pre12
2.3a < 2.3c
2.3pre1 < 2.3c
2.3pre1 < 2.3q
nix-env {--uninstall | -e}
drvnames...
The uninstall operation creates a new user environment, based on the current
generation of the active profile, from which the store paths designated by the
symbolic names
names are removed.
$ nix-env --uninstall gcc
$ nix-env -e '.*' (remove everything)
nix-env --set drvname
The
--set operation modifies the current generation of a profile so that
it contains exactly the specified derivation, and nothing else.
The following updates a profile such that its current generation will contain
just Firefox:
$ nix-env -p /nix/var/nix/profiles/browser --set firefox
nix-env --set-flag name value
drvnames...
The
--set-flag operation allows meta attributes of installed packages to
be modified. There are several attributes that can be usefully modified,
because they affect the behaviour of
nix-env or the user environment
build script:
•priority can be changed to resolve
filename clashes. The user environment build script uses the
meta.priority attribute of derivations to resolve filename collisions
between packages. Lower priority values denote a higher priority. For
instance, the GCC wrapper package and the Binutils package in Nixpkgs both
have a file bin/ld, so previously if you tried to install both you would get a
collision. Now, on the other hand, the GCC wrapper declares a higher priority
than Binutils, so the former’s bin/ld is symlinked in the user
environment.
•keep can be set to true to prevent the
package from being upgraded or replaced. This is useful if you want to hang on
to an older version of a package.
•active can be set to false to
“disable” the package. That is, no symlinks will be generated to
the files of the package, but it remains part of the profile (so it
won’t be garbage-collected). It can be set back to true to re-enable
the package.
To prevent the currently installed Firefox from being upgraded:
$ nix-env --set-flag keep true firefox
After this,
nix-env -u will ignore Firefox.
To disable the currently installed Firefox, then install a new Firefox while the
old remains part of the profile:
$ nix-env -q
firefox-2.0.0.9 (the current one)
$ nix-env --preserve-installed -i firefox-2.0.0.11
installing `firefox-2.0.0.11'
building path(s) `/nix/store/myy0y59q3ig70dgq37jqwg1j0rsapzsl-user-environment'
collision between `/nix/store/ ...-firefox-2.0.0.11/bin/firefox'
and `/nix/store/ ...-firefox-2.0.0.9/bin/firefox'.
(i.e., can’t have two active at the same time)
$ nix-env --set-flag active false firefox
setting flag on `firefox-2.0.0.9'
$ nix-env --preserve-installed -i firefox-2.0.0.11
installing `firefox-2.0.0.11'
$ nix-env -q
firefox-2.0.0.11 (the enabled one)
firefox-2.0.0.9 (the disabled one)
To make files from binutils take precedence over files from gcc:
$ nix-env --set-flag priority 5 binutils
$ nix-env --set-flag priority 10 gcc
nix-env {
--query |
-q} [
--installed
|
--available |
-a]
[{
--status |
-s}]
[{
--attr-path |
-P}] [
--no-name]
[{
--compare-versions |
-c}] [
--system]
[
--drv-path] [
--out-path] [
--description] [
--meta]
[
--xml] [
--json]
[{
--prebuilt-only |
-b}] [{
--attr |
-A}
attribute-path]
names...
The query operation displays information about either the store paths that are
installed in the current generation of the active profile (
--installed), or the derivations that are available for installation in
the active Nix expression (
--available). It only prints information
about derivations whose symbolic name matches one of
names.
The derivations are sorted by their name attributes.
The following flags specify the set of things on which the query operates.
--installed
The query operates on the store paths that are installed
in the current generation of the active profile. This is the default.
--available,
-a
The query operates on the derivations that are available
in the active Nix expression.
The following flags specify what information to display about the selected
derivations. Multiple flags may be specified, in which case the information is
shown in the order given here. Note that the name of the derivation is shown
unless
--no-name is specified.
--xml
Print the result in an XML representation suitable for
automatic processing by other tools. The root element is called items, which
contains a item element for each available or installed derivation. The fields
discussed below are all stored in attributes of the item elements.
--json
Print the result in a JSON representation suitable for
automatic processing by other tools.
--prebuilt-only /
-b
Show only derivations for which a substitute is
registered, i.e., there is a pre-built binary available that can be downloaded
in lieu of building the derivation. Thus, this shows all packages that
probably can be installed quickly.
--status,
-s
Print the status of the derivation. The status
consists of three characters. The first is I or -, indicating whether the
derivation is currently installed in the current generation of the active
profile. This is by definition the case for --installed, but not for
--available. The second is P or -, indicating whether the derivation is
present on the system. This indicates whether installation of an available
derivation will require the derivation to be built. The third is S or -,
indicating whether a substitute is available for the derivation.
--attr-path,
-P
Print the attribute path of the derivation, which
can be used to unambiguously select it using the --attr option
available in commands that install derivations like nix-env --install.
--no-name
Suppress printing of the name attribute of each
derivation.
--compare-versions /
-c
Compare installed versions to available versions, or vice
versa (if
--available is given). This is useful for quickly seeing
whether upgrades for installed packages are available in a Nix expression. A
column is added with the following meaning:
<
version
A newer version of the package is available or
installed.
=
version
At most the same version of the package is available or
installed.
>
version
Only older versions of the package are available or
installed.
- ?
No version of the package is available or
installed.
--system
Print the system attribute of the derivation.
--drv-path
Print the path of the store derivation.
--out-path
Print the output path of the derivation.
--description
Print a short (one-line) description of the derivation,
if available. The description is taken from the meta.description attribute of
the derivation.
--meta
Print all of the meta-attributes of the derivation. This
option is only available with --xml or --json.
To show installed packages:
$ nix-env -q
bison-1.875c
docbook-xml-4.2
firefox-1.0.4
MPlayer-1.0pre7
ORBit2-2.8.3
...
To show available packages:
$ nix-env -qa
firefox-1.0.7
GConf-2.4.0.1
MPlayer-1.0pre7
ORBit2-2.8.3
...
To show the status of available packages:
$ nix-env -qas
-P- firefox-1.0.7 (not installed but present)
--S GConf-2.4.0.1 (not present, but there is a substitute for fast installation)
--S MPlayer-1.0pre3 (i.e., this is not the installed MPlayer, even though the version is the same!)
IP- ORBit2-2.8.3 (installed and by definition present)
...
To show available packages in the Nix expression foo.nix:
$ nix-env -f ./foo.nix -qa
foo-1.2.3
To compare installed versions to what’s available:
$ nix-env -qc
...
acrobat-reader-7.0 - ? (package is not available at all)
autoconf-2.59 = 2.59 (same version)
firefox-1.0.4 < 1.0.7 (a more recent version is available)
...
To show all packages with “zip” in the name:
$ nix-env -qa '.*zip.*'
bzip2-1.0.6
gzip-1.6
zip-3.0
...
To show all packages with “firefox” or “chromium” in
the name:
$ nix-env -qa '.*(firefox|chromium).*'
chromium-37.0.2062.94
chromium-beta-38.0.2125.24
firefox-32.0.3
firefox-with-plugins-13.0.1
...
To show all packages in the latest revision of the Nixpkgs repository:
$ nix-env -f https://github.com/NixOS/nixpkgs/archive/master.tar.gz -qa
nix-env {--switch-profile | -S}
{path}
This operation makes
path the current profile for the user. That is, the
symlink ~/.nix-profile is made to point to
path.
$ nix-env -S ~/my-profile
nix-env --list-generations
This operation print a list of all the currently existing generations for the
active profile. These may be switched to using the
--switch-generation
operation. It also prints the creation date of the generation, and indicates
the current generation.
$ nix-env --list-generations
95 2004-02-06 11:48:24
96 2004-02-06 11:49:01
97 2004-02-06 16:22:45
98 2004-02-06 16:24:33 (current)
nix-env --delete-generations
generations...
This operation deletes the specified generations of the current profile. The
generations can be a list of generation numbers, the special value old to
delete all non-current generations, a value such as 30d to delete all
generations older than the specified number of days (except for the generation
that was active at that point in time), or a value such as. +5 to only keep
the specified items older than the current generation. Periodically deleting
old generations is important to make garbage collection effective.
$ nix-env --delete-generations 3 4 8
$ nix-env --delete-generations +5
$ nix-env --delete-generations 30d
$ nix-env -p other_profile --delete-generations old
nix-env {--switch-generation | -G}
{generation}
This operation makes generation number
generation the current generation
of the active profile. That is, if the
profile is the path to the
active profile, then the symlink
profile is made to point to
profile-
generation-link, which is in turn a symlink to the
actual user environment in the Nix store.
Switching will fail if the specified generation does not exist.
$ nix-env -G 42
switching from generation 50 to 42
nix-env --rollback
This operation switches to the “previous” generation of the active
profile, that is, the highest numbered generation lower than the current
generation, if it exists. It is just a convenience wrapper around
--list-generations and
--switch-generation.
$ nix-env --rollback
switching from generation 92 to 91
$ nix-env --rollback
error: no generation older than the current (91) exists
NIX_PROFILE
Location of the Nix profile. Defaults to the target of
the symlink ~/.nix-profile, if it exists, or /nix/var/nix/profiles/default
otherwise.
IN_NIX_SHELL
Indicator that tells if the current environment was set
up by nix-shell.
NIX_PATH
A colon-separated list of directories used to look up Nix
expressions enclosed in angle brackets (i.e., <
path>). For
instance, the value
/home/eelco/Dev:/etc/nixos
will cause Nix to look for paths relative to /home/eelco/Dev and /etc/nixos, in
that order. It is also possible to match paths against a prefix. For example,
the value
nixpkgs=/home/eelco/Dev/nixpkgs-branch:/etc/nixos
will cause Nix to search for <nixpkgs/
path> in
/home/eelco/Dev/nixpkgs-branch/
path and /etc/nixos/nixpkgs/
path.
If a path in the Nix search path starts with http:// or https://, it is
interpreted as the URL of a tarball that will be downloaded and unpacked to a
temporary location. The tarball must consist of a single top-level directory.
For example, setting
NIX_PATH to
nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/nixos-14.12.tar.gz
tells Nix to download the latest revision in the Nixpkgs/NixOS 14.12 channel.
The search path can be extended using the
-I option, which takes
precedence over
NIX_PATH.
NIX_IGNORE_SYMLINK_STORE
Normally, the Nix store directory (typically /nix/store)
is not allowed to contain any symlink components. This is to prevent
“impure” builds. Builders sometimes “canonicalise”
paths by resolving all symlink components. Thus, builds on different machines
(with /nix/store resolving to different locations) could yield different
results. This is generally not a problem, except when builds are deployed to
machines where /nix/store resolves differently. If you are sure that
you’re not going to do that, you can set
NIX_IGNORE_SYMLINK_STORE to
1.
Note that if you’re symlinking the Nix store so that you can put it on
another file system than the root file system, on Linux you’re better
off using bind mount points, e.g.,
$ mkdir /nix
$ mount -o bind /mnt/otherdisk/nix /nix
Consult the
mount(8) manual page for details.
NIX_STORE_DIR
Overrides the location of the Nix store (default
prefix/store).
NIX_DATA_DIR
Overrides the location of the Nix static data directory
(default prefix/share).
NIX_LOG_DIR
Overrides the location of the Nix log directory (default
prefix/log/nix).
NIX_STATE_DIR
Overrides the location of the Nix state directory
(default prefix/var/nix).
NIX_CONF_DIR
Overrides the location of the Nix configuration directory
(default prefix/etc/nix).
TMPDIR
Use the specified directory to store temporary files. In
particular, this includes temporary build directories; these can take up
substantial amounts of disk space. The default is /tmp.
NIX_REMOTE
This variable should be set to daemon if you want to use
the Nix daemon to execute Nix operations. This is necessary in multi-user Nix
installations. If the Nix daemon's Unix socket is at some non-standard path,
this variable should be set to unix://path/to/socket. Otherwise, it should be
left unset.
NIX_SHOW_STATS
If set to 1, Nix will print some evaluation statistics,
such as the number of values allocated.
NIX_COUNT_CALLS
If set to 1, Nix will print how often functions were
called during Nix expression evaluation. This is useful for profiling your Nix
expressions.
GC_INITIAL_HEAP_SIZE
If Nix has been configured to use the Boehm garbage
collector, this variable sets the initial size of the heap in bytes. It
defaults to 384 MiB. Setting it to a low value reduces memory consumption, but
will increase runtime due to the overhead of garbage collection.
Eelco Dolstra
Author
Copyright © 2004-2018 Eelco Dolstra