常量

nothing

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.

PROGRAM_FILE

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 @__FILE__.

ARGS

An array of the command line arguments passed to Julia, as strings.

C_NULL

The C null pointer constant, sometimes used when calling external code.

VERSION

A VersionNumber object describing which version of Julia is in use. For details see Version Number Literals.

LOAD_PATH

An array of paths for using and 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_PROJECT environment variable or the --project command-line option.

• @stdlib expands to the absolute path of the current Julia installation's standard library directory.

• @name refers to a named environment, which are stored in depots (see JULIA_DEPOT_PATH) under the environments subdirectory. The user's named environments are stored in ~/.julia/environments so @name would refer to the environment in ~/.julia/environments/name if it exists and contains a Project.toml file. If name contains # 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 @v#.# expands to @v1.2 and will look for an environment by that name, typically at ~/.julia/environments/v1.2.

The fully expanded value of LOAD_PATH that is searched for projects and packages can be seen by calling the Base.load_path() function.

See also: JULIA_LOAD_PATH, JULIA_PROJECT, JULIA_DEPOT_PATH, and Code Loading.

Sys.BINDIR

A string containing the full path to the directory containing the julia executable.

Sys.CPU_THREADS

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.

Sys.WORD_SIZE

Standard word size on the current machine, in bits.

Sys.KERNEL

A symbol representing the name of the operating system, as returned by uname of the build configuration.

Sys.ARCH

A symbol representing the architecture of the build configuration.

Sys.MACHINE

A string containing the build triple.