Janet 1.11.1-4cc6809 Documentation
(Other Versions: 1.10.1 1.9.1 1.8.1 1.7.0 1.6.0 1.5.1 1.5.0 1.4.0 1.3.1 )

OS Module

The os module contains most Operating System specific functionality as well as routines for interacting with the host OS. There is also some functionality for interacting with the file system. The functionality in this module can be much reduced by setting the JANET_REDUCED_OS define in janetconf.h.


os/arch os/cd os/chmod os/clock os/cryptorand os/cwd os/date os/dir os/environ os/execute os/exit os/getenv os/link os/lstat os/mkdir os/mktime os/perm-int os/perm-string os/readlink os/realpath os/rename os/rm os/rmdir os/setenv os/shell os/sleep os/stat os/symlink os/time os/touch os/umask os/which

os/arch cfunction

Check the ISA that janet was compiled for. Returns one of:

Community Examples

os/cd cfunction
(os/cd path)

Change current directory to path. Returns nil on success, errors on failure.
Community Examples

os/chmod cfunction
(os/chmod path mode)

Change file permissions, where mode is a permission string as returned by os/perm-string, or an integer as returned by os/perm-int. When mode is an integer, it is interpreted as a Unix permission value, best specified in octal, like 8r666 or 8r400. Windows will not differentiate between user, group, and other permissions, and thus will combine all of these permissions. Returns nil.
Community Examples

os/clock cfunction

Return the number of seconds since some fixed point in time. The clock is guaranteed to be non decreasing in real time.
Community Examples

os/cryptorand cfunction
(os/cryptorand n &opt buf)

Get or append n bytes of good quality random data provided by the OS. Returns a new buffer or buf.
Community Examples

os/cwd cfunction

Returns the current working directory.
Community Examples

os/date cfunction
(os/date &opt time local)

Returns the given time as a date struct, or the current time if no time is given. Returns a struct with following key values. Note that all numbers are 0-indexed. Date is given in UTC unless local is truthy, in which case the date is formatted for the local timezone.

	:seconds - number of seconds [0-61]
	:minutes - number of minutes [0-59]
	:hours - number of hours [0-23]
	:month-day - day of month [0-30]
	:month - month of year [0, 11]
	:year - years since year 0 (e.g. 2019)
	:week-day - day of the week [0-6]
	:year-day - day of the year [0-365]
	:dst - If Day Light Savings is in effect
Community Examples

os/dir cfunction
(os/dir dir &opt array)

Iterate over files and subdirectories in a directory. Returns an array of paths parts, with only the file name or directory name and no prefix.
Community Examples

os/environ cfunction

Get a copy of the os environment table.
Community Examples

os/execute cfunction
(os/execute args &opts flags env)

Execute a program on the system and pass it string arguments. Flags is a keyword that modifies how the program will execute.

	:e - enables passing an environment to the program. Without :e, the current environment is inherited.
	:p - allows searching the current PATH for the binary to execute. Without this flag, binaries must use absolute paths.

env is a table or struct mapping environment variables to values. Returns the exit status of the program.
Community Examples

os/exit cfunction
(os/exit &opt x)

Exit from janet with an exit code equal to x. If x is not an integer, the exit with status equal the hash of x.
Community Examples

os/getenv cfunction
(os/getenv variable &opt dflt)

Get the string value of an environment variable.
Community Examples

os/link cfunction
(os/link oldpath newpath &opt symlink)

Create a link at newpath that points to oldpath and returns nil. Iff symlink is truthy, creates a symlink. Iff symlink is falsey or not provided, creates a hard link. Does not work on Windows.
Community Examples

os/lstat cfunction
(os/lstat path &opt tab|key)

Like os/stat, but don't follow symlinks.
Community Examples

os/mkdir cfunction
(os/mkdir path)

Create a new directory. The path will be relative to the current directory if relative, otherwise it will be an absolute path. Returns true if the directory was created, false if the directory already exists, and errors otherwise.
Community Examples

os/mktime cfunction
(os/mktime date-struct &opt local)

Get the broken down date-struct time expressed as the number of seconds since January 1, 1970, the Unix epoch. Returns a real number. Date is given in UTC unless local is truthy, in which case the date is computed for the local timezone.

Inverse function to os/date.
Community Examples

os/perm-int cfunction
(os/perm-int bytes)

Parse a 9 character permission string and return an integer that can be used by chmod.
Community Examples

os/perm-string cfunction
(os/perm-string int)

Convert a Unix octal permission value from a permission integer as returned by os/stat to a human readable string, that follows the formatting of unix tools like ls. Returns the string as a 9 character string of r, w, x and - characters. Does not include the file/directory/symlink character as rendered by `ls`.
Community Examples

os/readlink cfunction
(os/readlink path)

Read the contents of a symbolic link. Does not work on Windows.
Community Examples

os/realpath cfunction
(os/realpath path)

Get the absolute path for a given path, following ../, ./, and symlinks. Returns an absolute path as a string. Will raise an error on Windows.
Community Examples

os/rename cfunction
(os/rename oldname newname)

Rename a file on disk to a new path. Returns nil.
Community Examples

os/rm cfunction
(os/rm path)

Delete a file. Returns nil.
Community Examples

os/rmdir cfunction
(os/rmdir path)

Delete a directory. The directory must be empty to succeed.
Community Examples

os/setenv cfunction
(os/setenv variable value)

Set an environment variable.
Community Examples

os/shell cfunction
(os/shell str)

Pass a command string str directly to the system shell.
Community Examples

os/sleep cfunction
(os/sleep nsec)

Suspend the program for nsec seconds. 'nsec' can be a real number. Returns nil.
Community Examples

os/stat cfunction
(os/stat path &opt tab|key)

Gets information about a file or directory. Returns a table If the third argument is a keyword, returns only that information from stat. If the file or directory does not exist, returns nil. The keys are

	:dev - the device that the file is on
	:mode - the type of file, one of :file, :directory, :block, :character, :fifo, :socket, :link, or :other
	:int-permissions - A Unix permission integer like 8r744
	:permissions - A Unix permission string like "rwxr--r--"
	:uid - File uid
	:gid - File gid
	:nlink - number of links to file
	:rdev - Real device of file. 0 on windows.
	:size - size of file in bytes
	:blocks - number of blocks in file. 0 on windows
	:blocksize - size of blocks in file. 0 on windows
	:accessed - timestamp when file last accessed
	:changed - timestamp when file last changed (permissions changed)
	:modified - timestamp when file last modified (content changed)
Community Examples

os/symlink cfunction
(os/symlink oldpath newpath)

Create a symlink from oldpath to newpath, returning nil. Same as (os/link oldpath newpath true).
Community Examples

os/time cfunction

Get the current time expressed as the number of seconds since January 1, 1970, the Unix epoch. Returns a real number.
Community Examples

os/touch cfunction
(os/touch path &opt actime modtime)

Update the access time and modification times for a file. By default, sets times to the current time.
Community Examples

os/umask cfunction
(os/umask mask)

Set a new umask, returns the old umask.
Community Examples

os/which cfunction

Check the current operating system. Returns one of:

	:web - Web assembly (emscripten)
	:posix - A POSIX compatible system (default)

May also return a custom keyword specified at build time.
Community Examples