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julia - Man Page

a high-level, high-performance dynamic programming language for technical computing

Examples (TL;DR)


julia [OPTIONS...] -- [PROGRAMMFILE] [ARGS...]

If a Julia source file is given as a PROGRAMFILE (optionally followed by arguments in ARGS) Julia will execute the program and exit.


Julia is a high-level, high-performance dynamic programming language for technical computing, with syntax that is familiar to users of other technical computing environments. It provides a sophisticated compiler, distributed parallel execution, numerical accuracy, and an extensive mathematical function library. The library, largely written in Julia itself, also integrates mature, best-of-breed C and Fortran libraries for linear algebra, random number generation, signal processing, and string processing. In addition, the Julia developer community is contributing a number of external packages through Julia's built-in package manager at a rapid pace. Julia programs are organized around multiple dispatch; by defining functions and overloading them for different combinations of argument types, which can also be user-defined. For a more in-depth discussion of the rationale and advantages of Julia over other systems, please see the online manual: https://docs.julialang.org

Command-Line Options

-v,  --version

Display version information

-h,  --help

Print help message


Print uncommon options not shown by `-h`


Set <dir> as the active project/environment. The default @. option will search through parent directories until a Project.toml or JuliaProject.toml file is found.

-J,  --sysimage <file>

Start up with the given system image file

-H,  --home <dir>

Set location of julia executable


Load `JULIA_DEPOT_PATH/config/startup.jl`; if `JULIA_DEPOT_PATH` environment variable is unset, load `~/.julia/config/startup.jl`


Enable or disable Julia's default signal handlers


Use native code from system image if available


Enable or disable incremental precompilation of modules. The "existing" option allows use of existing compiled modules that were previously precompiled, but disallows creation of new precompile files. The "strict" option is similar, but will error if no precompile file is found.


Enable or disable usage of native code caching in the form of pkgimages

-e,  --eval <expr>

Evaluate <expr>

-E,  --print <expr>

Evaluate <expr> and display the result

-L,  --load <file>

Load <file> immediately on all processors

-t,  --threads <n>

Enable n threads; "auto" tries to infer a useful default number of threads to use but the exact behavior might change in the future. Currently, "auto" uses the number of CPUs assigned to this julia process based on the OS-specific affinity assignment interface, if supported (Linux and Windows). If this is not supported (macOS) or process affinity is not configured, it uses the number of CPU threads.


Use N threads for the mark phase of GC and M (0 or 1) threads for the concurrent sweeping phase of GC. N is set to half of the number of compute threads and M is set to 0 if unspecified.

-p,  --procs {N|auto}

Integer value N launches N additional local worker processes `auto` launches as many workers as the number of local CPU threads (logical cores)

--machine-file <file>

Run processes on hosts listed in <file>


Interactive mode; REPL runs and `isinteractive()` is true

-q,  --quiet

Quiet startup: no banner, suppress REPL warnings


Enable or disable startup banner


Enable or disable color text


Load or save history


Enable or disable syntax and method deprecation warnings (`error` turns warnings into errors)


Enable or disable method overwrite warnings


Enable or disable warning for ambiguous top-level scope

-C,  --cpu-target=<target>

Limit usage of CPU features up to <target>; set to `help` to see the available options

-O,  --optimize={0,1,2*,3}

Set the optimization level (level 3 if `-O` is used without a level)


Set a lower bound on the optimization level

-g {0,1*,2}

Set the level of debug info generation (level 2 if `-g` is used without a level)


Control whether inlining is permitted, including overriding @inline declarations


Emit bounds checks always, never, or respect @inbounds declarations


Disallow or enable unsafe floating point optimizations (overrides @fastmath declaration)


Count executions of source lines (omitting setting is equivalent to `user`)


Count executions of source lines in a file or files under a given directory. A `@` must be placed before the path to indicate this option. A `@` with no path will track the current directory.


Append coverage information to the LCOV tracefile (filename supports format tokens)


Count bytes allocated by each source line (omitting setting is equivalent to `user`)


Count bytes allocated by each source line in a file or files under a given directory. A `@` must be placed before the path to indicate this option. A `@` with no path will track the current directory.


Launch a bug report session. It can be used to start a REPL, run a script, or evaluate expressions. It first tries to use BugReporting.jl installed in current environment and fallbacks to the latest compatible BugReporting.jl if not. For more information, see --bug-report=help.


Forces garbage collection if memory usage is higher than the given value. The value may be specified as a number of bytes, optionally in units of KB, MB, GB, or TB, or as a percentage of physical memory with %.


Enable or disable JIT compiler, or request exhaustive or minimal compilation

--output-o <name>

Generate an object file (including system image data)

--output-ji <name>

Generate a system image data file (.ji)


Remove docstrings and source location info from system image


Remove IR (intermediate representation) of compiled functions

--output-unopt-bc <name>

Generate unoptimized LLVM bitcode (.bc)

--output-bc <name>

Generate LLVM bitcode (.bc)

--output-asm <name>

Generate an assembly file (.s)


Generate an incremental output file (rather than complete)


Print precompile statements for methods compiled during execution or save to a path


Force generate code in imaging mode

Files and Environment

See https://docs.julialang.org/en/v1/manual/environment-variables/


Please report any bugs using the GitHub issue tracker: https://github.com/julialang/julia/issues?state=open


Contributors: https://github.com/JuliaLang/julia/graphs/contributors

Internet Resources

Website:  https://julialang.org/
Documentation:  https://docs.julialang.org/
Downloads:  https://julialang.org/downloads/


Julia is an open-source project. It is made available under the MIT license.


2023-09-01 JULIA