The singleton instance of type
Nothing, used by convention when there is no value to return (as in a C
void function) or when a variable or field holds no value.
A string containing the script name passed to Julia from the command line. Note that the script name remains unchanged from within included files. Alternatively see
An array of the command line arguments passed to Julia, as strings.
The C null pointer constant, sometimes used when calling external code.
VersionNumber object describing which version of Julia is in use. See also Version Number Literals.
A stack of "depot" locations where the package manager, as well as Julia's code loading mechanisms, look for package registries, installed packages, named environments, repo clones, cached compiled package images, and configuration files. By default it includes:
~is the user home as appropriate on the system;
- an architecture-specific shared system directory, e.g.
- an architecture-independent shared system directory, e.g.
DEPOT_PATH might be:
[joinpath(homedir(), ".julia"), "/usr/local/share/julia", "/usr/share/julia"]
The first entry is the "user depot" and should be writable by and owned by the current user. The user depot is where: registries are cloned, new package versions are installed, named environments are created and updated, package repos are cloned, newly compiled package image files are saved, log files are written, development packages are checked out by default, and global configuration data is saved. Later entries in the depot path are treated as read-only and are appropriate for registries, packages, etc. installed and managed by system administrators.
DEPOT_PATH is populated based on the
JULIA_DEPOT_PATH environment variable if set.
Each entry in
DEPOT_PATH is a path to a directory which contains subdirectories used by Julia for various purposes. Here is an overview of some of the subdirectories that may exist in a depot:
clones: Contains full clones of package repos. Maintained by
Pkg.jland used as a cache.
compiled: Contains precompiled
*.jifiles for packages. Maintained by Julia.
dev: Default directory for
Pkg.develop. Maintained by
Pkg.jland the user.
environments: Default package environments. For instance the global environment for a specific julia version. Maintained by
logs: Contains logs of
REPLoperations. Maintained by
packages: Contains packages, some of which were explicitly installed and some which are implicit dependencies. Maintained by
registries: Contains package registries. By default only
General. Maintained by
JULIA_DEPOT_PATH, and Code Loading.
An array of paths for
import statements to consider as project environments or package directories when loading code. It is populated based on the
JULIA_LOAD_PATH environment variable if set; otherwise it defaults to
["@", "@v#.#", "@stdlib"]. Entries starting with
@ have special meanings:
@refers to the "current active environment", the initial value of which is initially determined by the
JULIA_PROJECTenvironment variable or the
@stdlibexpands to the absolute path of the current Julia installation's standard library directory.
@namerefers to a named environment, which are stored in depots (see
JULIA_DEPOT_PATH) under the
environmentssubdirectory. The user's named environments are stored in
@namewould refer to the environment in
~/.julia/environments/nameif it exists and contains a
#characters, then they are replaced with the major, minor and patch components of the Julia version number. For example, if you are running Julia 1.2 then
@v1.2and will look for an environment by that name, typically at
The fully expanded value of
LOAD_PATH that is searched for projects and packages can be seen by calling the
JULIA_DEPOT_PATH, and Code Loading.
A string containing the full path to the directory containing the
The number of logical CPU cores available in the system, i.e. the number of threads that the CPU can run concurrently. Note that this is not necessarily the number of CPU cores, for example, in the presence of hyper-threading.
See Hwloc.jl or CpuId.jl for extended information, including number of physical cores.
Standard word size on the current machine, in bits.
A symbol representing the name of the operating system, as returned by
uname of the build configuration.
A symbol representing the architecture of the build configuration.
A string containing the build triple.