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os.dup2(fd, fd2, inheritable=True) Duplicate file descriptor fd to fd2, closing the latter first if necessary. Return fd2. The new file descriptor is inheritable by default or non-inheritable if inheritable is False. Changed in version 3.4: Add the optional inheritable parameter. Changed in version 3.7: Return fd2...
python.library.os#os.dup2
os.environ A mapping object representing the string environment. For example, environ['HOME'] is the pathname of your home directory (on some platforms), and is equivalent to getenv("HOME") in C. This mapping is captured the first time the os module is imported, typically during Python startup as part of processing s...
python.library.os#os.environ
os.environb Bytes version of environ: a mapping object representing the environment as byte strings. environ and environb are synchronized (modify environb updates environ, and vice versa). environb is only available if supports_bytes_environ is True. New in version 3.2. Changed in version 3.9: Updated to support ...
python.library.os#os.environb
exception os.error An alias for the built-in OSError exception.
python.library.os#os.error
os.execl(path, arg0, arg1, ...) os.execle(path, arg0, arg1, ..., env) os.execlp(file, arg0, arg1, ...) os.execlpe(file, arg0, arg1, ..., env) os.execv(path, args) os.execve(path, args, env) os.execvp(file, args) os.execvpe(file, args, env) These functions all execute a new program, replacing the current...
python.library.os#os.execl
os.execl(path, arg0, arg1, ...) os.execle(path, arg0, arg1, ..., env) os.execlp(file, arg0, arg1, ...) os.execlpe(file, arg0, arg1, ..., env) os.execv(path, args) os.execve(path, args, env) os.execvp(file, args) os.execvpe(file, args, env) These functions all execute a new program, replacing the current...
python.library.os#os.execle
os.execl(path, arg0, arg1, ...) os.execle(path, arg0, arg1, ..., env) os.execlp(file, arg0, arg1, ...) os.execlpe(file, arg0, arg1, ..., env) os.execv(path, args) os.execve(path, args, env) os.execvp(file, args) os.execvpe(file, args, env) These functions all execute a new program, replacing the current...
python.library.os#os.execlp
os.execl(path, arg0, arg1, ...) os.execle(path, arg0, arg1, ..., env) os.execlp(file, arg0, arg1, ...) os.execlpe(file, arg0, arg1, ..., env) os.execv(path, args) os.execve(path, args, env) os.execvp(file, args) os.execvpe(file, args, env) These functions all execute a new program, replacing the current...
python.library.os#os.execlpe
os.execl(path, arg0, arg1, ...) os.execle(path, arg0, arg1, ..., env) os.execlp(file, arg0, arg1, ...) os.execlpe(file, arg0, arg1, ..., env) os.execv(path, args) os.execve(path, args, env) os.execvp(file, args) os.execvpe(file, args, env) These functions all execute a new program, replacing the current...
python.library.os#os.execv
os.execl(path, arg0, arg1, ...) os.execle(path, arg0, arg1, ..., env) os.execlp(file, arg0, arg1, ...) os.execlpe(file, arg0, arg1, ..., env) os.execv(path, args) os.execve(path, args, env) os.execvp(file, args) os.execvpe(file, args, env) These functions all execute a new program, replacing the current...
python.library.os#os.execve
os.execl(path, arg0, arg1, ...) os.execle(path, arg0, arg1, ..., env) os.execlp(file, arg0, arg1, ...) os.execlpe(file, arg0, arg1, ..., env) os.execv(path, args) os.execve(path, args, env) os.execvp(file, args) os.execvpe(file, args, env) These functions all execute a new program, replacing the current...
python.library.os#os.execvp
os.execl(path, arg0, arg1, ...) os.execle(path, arg0, arg1, ..., env) os.execlp(file, arg0, arg1, ...) os.execlpe(file, arg0, arg1, ..., env) os.execv(path, args) os.execve(path, args, env) os.execvp(file, args) os.execvpe(file, args, env) These functions all execute a new program, replacing the current...
python.library.os#os.execvpe
os.extsep The character which separates the base filename from the extension; for example, the '.' in os.py. Also available via os.path.
python.library.os#os.extsep
os.EX_CANTCREAT Exit code that means a user specified output file could not be created. Availability: Unix.
python.library.os#os.EX_CANTCREAT
os.EX_CONFIG Exit code that means that some kind of configuration error occurred. Availability: Unix.
python.library.os#os.EX_CONFIG
os.EX_DATAERR Exit code that means the input data was incorrect. Availability: Unix.
python.library.os#os.EX_DATAERR
os.EX_IOERR Exit code that means that an error occurred while doing I/O on some file. Availability: Unix.
python.library.os#os.EX_IOERR
os.EX_NOHOST Exit code that means a specified host did not exist. Availability: Unix.
python.library.os#os.EX_NOHOST
os.EX_NOINPUT Exit code that means an input file did not exist or was not readable. Availability: Unix.
python.library.os#os.EX_NOINPUT
os.EX_NOPERM Exit code that means that there were insufficient permissions to perform the operation (but not intended for file system problems). Availability: Unix.
python.library.os#os.EX_NOPERM
os.EX_NOTFOUND Exit code that means something like “an entry was not found”. Availability: Unix.
python.library.os#os.EX_NOTFOUND
os.EX_NOUSER Exit code that means a specified user did not exist. Availability: Unix.
python.library.os#os.EX_NOUSER
os.EX_OK Exit code that means no error occurred. Availability: Unix.
python.library.os#os.EX_OK
os.EX_OSERR Exit code that means an operating system error was detected, such as the inability to fork or create a pipe. Availability: Unix.
python.library.os#os.EX_OSERR
os.EX_OSFILE Exit code that means some system file did not exist, could not be opened, or had some other kind of error. Availability: Unix.
python.library.os#os.EX_OSFILE
os.EX_PROTOCOL Exit code that means that a protocol exchange was illegal, invalid, or not understood. Availability: Unix.
python.library.os#os.EX_PROTOCOL
os.EX_SOFTWARE Exit code that means an internal software error was detected. Availability: Unix.
python.library.os#os.EX_SOFTWARE
os.EX_TEMPFAIL Exit code that means a temporary failure occurred. This indicates something that may not really be an error, such as a network connection that couldn’t be made during a retryable operation. Availability: Unix.
python.library.os#os.EX_TEMPFAIL
os.EX_UNAVAILABLE Exit code that means that a required service is unavailable. Availability: Unix.
python.library.os#os.EX_UNAVAILABLE
os.EX_USAGE Exit code that means the command was used incorrectly, such as when the wrong number of arguments are given. Availability: Unix.
python.library.os#os.EX_USAGE
os.fchdir(fd) Change the current working directory to the directory represented by the file descriptor fd. The descriptor must refer to an opened directory, not an open file. As of Python 3.3, this is equivalent to os.chdir(fd). Raises an auditing event os.chdir with argument path. Availability: Unix.
python.library.os#os.fchdir
os.fchmod(fd, mode) Change the mode of the file given by fd to the numeric mode. See the docs for chmod() for possible values of mode. As of Python 3.3, this is equivalent to os.chmod(fd, mode). Raises an auditing event os.chmod with arguments path, mode, dir_fd. Availability: Unix.
python.library.os#os.fchmod
os.fchown(fd, uid, gid) Change the owner and group id of the file given by fd to the numeric uid and gid. To leave one of the ids unchanged, set it to -1. See chown(). As of Python 3.3, this is equivalent to os.chown(fd, uid, gid). Raises an auditing event os.chown with arguments path, uid, gid, dir_fd. Availability:...
python.library.os#os.fchown
os.fdatasync(fd) Force write of file with filedescriptor fd to disk. Does not force update of metadata. Availability: Unix. Note This function is not available on MacOS.
python.library.os#os.fdatasync
os.fdopen(fd, *args, **kwargs) Return an open file object connected to the file descriptor fd. This is an alias of the open() built-in function and accepts the same arguments. The only difference is that the first argument of fdopen() must always be an integer.
python.library.os#os.fdopen
os.fork() Fork a child process. Return 0 in the child and the child’s process id in the parent. If an error occurs OSError is raised. Note that some platforms including FreeBSD <= 6.3 and Cygwin have known issues when using fork() from a thread. Raises an auditing event os.fork with no arguments. Changed in version ...
python.library.os#os.fork
os.forkpty() Fork a child process, using a new pseudo-terminal as the child’s controlling terminal. Return a pair of (pid, fd), where pid is 0 in the child, the new child’s process id in the parent, and fd is the file descriptor of the master end of the pseudo-terminal. For a more portable approach, use the pty modul...
python.library.os#os.forkpty
os.fpathconf(fd, name) Return system configuration information relevant to an open file. name specifies the configuration value to retrieve; it may be a string which is the name of a defined system value; these names are specified in a number of standards (POSIX.1, Unix 95, Unix 98, and others). Some platforms define...
python.library.os#os.fpathconf
os.fsdecode(filename) Decode the path-like filename from the filesystem encoding with 'surrogateescape' error handler, or 'strict' on Windows; return str unchanged. fsencode() is the reverse function. New in version 3.2. Changed in version 3.6: Support added to accept objects implementing the os.PathLike interface...
python.library.os#os.fsdecode
os.fsencode(filename) Encode path-like filename to the filesystem encoding with 'surrogateescape' error handler, or 'strict' on Windows; return bytes unchanged. fsdecode() is the reverse function. New in version 3.2. Changed in version 3.6: Support added to accept objects implementing the os.PathLike interface.
python.library.os#os.fsencode
os.fspath(path) Return the file system representation of the path. If str or bytes is passed in, it is returned unchanged. Otherwise __fspath__() is called and its value is returned as long as it is a str or bytes object. In all other cases, TypeError is raised. New in version 3.6.
python.library.os#os.fspath
os.fstat(fd) Get the status of the file descriptor fd. Return a stat_result object. As of Python 3.3, this is equivalent to os.stat(fd). See also The stat() function.
python.library.os#os.fstat
os.fstatvfs(fd) Return information about the filesystem containing the file associated with file descriptor fd, like statvfs(). As of Python 3.3, this is equivalent to os.statvfs(fd). Availability: Unix.
python.library.os#os.fstatvfs
os.fsync(fd) Force write of file with filedescriptor fd to disk. On Unix, this calls the native fsync() function; on Windows, the MS _commit() function. If you’re starting with a buffered Python file object f, first do f.flush(), and then do os.fsync(f.fileno()), to ensure that all internal buffers associated with f ...
python.library.os#os.fsync
os.ftruncate(fd, length) Truncate the file corresponding to file descriptor fd, so that it is at most length bytes in size. As of Python 3.3, this is equivalent to os.truncate(fd, length). Raises an auditing event os.truncate with arguments fd, length. Availability: Unix, Windows. Changed in version 3.5: Added suppo...
python.library.os#os.ftruncate
os.fwalk(top='.', topdown=True, onerror=None, *, follow_symlinks=False, dir_fd=None) This behaves exactly like walk(), except that it yields a 4-tuple (dirpath, dirnames, filenames, dirfd), and it supports dir_fd. dirpath, dirnames and filenames are identical to walk() output, and dirfd is a file descriptor referring...
python.library.os#os.fwalk
os.F_LOCK os.F_TLOCK os.F_ULOCK os.F_TEST Flags that specify what action lockf() will take. Availability: Unix. New in version 3.3.
python.library.os#os.F_LOCK
os.F_OK os.R_OK os.W_OK os.X_OK Values to pass as the mode parameter of access() to test the existence, readability, writability and executability of path, respectively.
python.library.os#os.F_OK
os.F_LOCK os.F_TLOCK os.F_ULOCK os.F_TEST Flags that specify what action lockf() will take. Availability: Unix. New in version 3.3.
python.library.os#os.F_TEST
os.F_LOCK os.F_TLOCK os.F_ULOCK os.F_TEST Flags that specify what action lockf() will take. Availability: Unix. New in version 3.3.
python.library.os#os.F_TLOCK
os.F_LOCK os.F_TLOCK os.F_ULOCK os.F_TEST Flags that specify what action lockf() will take. Availability: Unix. New in version 3.3.
python.library.os#os.F_ULOCK
os.getcwd() Return a string representing the current working directory.
python.library.os#os.getcwd
os.getcwdb() Return a bytestring representing the current working directory. Changed in version 3.8: The function now uses the UTF-8 encoding on Windows, rather than the ANSI code page: see PEP 529 for the rationale. The function is no longer deprecated on Windows.
python.library.os#os.getcwdb
os.getegid() Return the effective group id of the current process. This corresponds to the “set id” bit on the file being executed in the current process. Availability: Unix.
python.library.os#os.getegid
os.getenv(key, default=None) Return the value of the environment variable key if it exists, or default if it doesn’t. key, default and the result are str. On Unix, keys and values are decoded with sys.getfilesystemencoding() and 'surrogateescape' error handler. Use os.getenvb() if you would like to use a different en...
python.library.os#os.getenv
os.getenvb(key, default=None) Return the value of the environment variable key if it exists, or default if it doesn’t. key, default and the result are bytes. getenvb() is only available if supports_bytes_environ is True. Availability: most flavors of Unix. New in version 3.2.
python.library.os#os.getenvb
os.geteuid() Return the current process’s effective user id. Availability: Unix.
python.library.os#os.geteuid
os.getgid() Return the real group id of the current process. Availability: Unix.
python.library.os#os.getgid
os.getgrouplist(user, group) Return list of group ids that user belongs to. If group is not in the list, it is included; typically, group is specified as the group ID field from the password record for user. Availability: Unix. New in version 3.3.
python.library.os#os.getgrouplist
os.getgroups() Return list of supplemental group ids associated with the current process. Availability: Unix. Note On Mac OS X, getgroups() behavior differs somewhat from other Unix platforms. If the Python interpreter was built with a deployment target of 10.5 or earlier, getgroups() returns the list of effective g...
python.library.os#os.getgroups
os.getloadavg() Return the number of processes in the system run queue averaged over the last 1, 5, and 15 minutes or raises OSError if the load average was unobtainable. Availability: Unix.
python.library.os#os.getloadavg
os.getlogin() Return the name of the user logged in on the controlling terminal of the process. For most purposes, it is more useful to use getpass.getuser() since the latter checks the environment variables LOGNAME or USERNAME to find out who the user is, and falls back to pwd.getpwuid(os.getuid())[0] to get the log...
python.library.os#os.getlogin
os.getpgid(pid) Return the process group id of the process with process id pid. If pid is 0, the process group id of the current process is returned. Availability: Unix.
python.library.os#os.getpgid
os.getpgrp() Return the id of the current process group. Availability: Unix.
python.library.os#os.getpgrp
os.getpid() Return the current process id.
python.library.os#os.getpid
os.getppid() Return the parent’s process id. When the parent process has exited, on Unix the id returned is the one of the init process (1), on Windows it is still the same id, which may be already reused by another process. Availability: Unix, Windows. Changed in version 3.2: Added support for Windows.
python.library.os#os.getppid
os.getpriority(which, who) Get program scheduling priority. The value which is one of PRIO_PROCESS, PRIO_PGRP, or PRIO_USER, and who is interpreted relative to which (a process identifier for PRIO_PROCESS, process group identifier for PRIO_PGRP, and a user ID for PRIO_USER). A zero value for who denotes (respectively...
python.library.os#os.getpriority
os.getrandom(size, flags=0) Get up to size random bytes. The function can return less bytes than requested. These bytes can be used to seed user-space random number generators or for cryptographic purposes. getrandom() relies on entropy gathered from device drivers and other sources of environmental noise. Unnecessar...
python.library.os#os.getrandom
os.getresgid() Return a tuple (rgid, egid, sgid) denoting the current process’s real, effective, and saved group ids. Availability: Unix. New in version 3.2.
python.library.os#os.getresgid
os.getresuid() Return a tuple (ruid, euid, suid) denoting the current process’s real, effective, and saved user ids. Availability: Unix. New in version 3.2.
python.library.os#os.getresuid
os.getsid(pid) Call the system call getsid(). See the Unix manual for the semantics. Availability: Unix.
python.library.os#os.getsid
os.getuid() Return the current process’s real user id. Availability: Unix.
python.library.os#os.getuid
os.getxattr(path, attribute, *, follow_symlinks=True) Return the value of the extended filesystem attribute attribute for path. attribute can be bytes or str (directly or indirectly through the PathLike interface). If it is str, it is encoded with the filesystem encoding. This function can support specifying a file d...
python.library.os#os.getxattr
os.get_blocking(fd) Get the blocking mode of the file descriptor: False if the O_NONBLOCK flag is set, True if the flag is cleared. See also set_blocking() and socket.socket.setblocking(). Availability: Unix. New in version 3.5.
python.library.os#os.get_blocking
os.get_exec_path(env=None) Returns the list of directories that will be searched for a named executable, similar to a shell, when launching a process. env, when specified, should be an environment variable dictionary to lookup the PATH in. By default, when env is None, environ is used. New in version 3.2.
python.library.os#os.get_exec_path
os.get_handle_inheritable(handle) Get the “inheritable” flag of the specified handle (a boolean). Availability: Windows.
python.library.os#os.get_handle_inheritable
os.get_inheritable(fd) Get the “inheritable” flag of the specified file descriptor (a boolean).
python.library.os#os.get_inheritable
os.get_terminal_size(fd=STDOUT_FILENO) Return the size of the terminal window as (columns, lines), tuple of type terminal_size. The optional argument fd (default STDOUT_FILENO, or standard output) specifies which file descriptor should be queried. If the file descriptor is not connected to a terminal, an OSError is r...
python.library.os#os.get_terminal_size
os.GRND_NONBLOCK By default, when reading from /dev/random, getrandom() blocks if no random bytes are available, and when reading from /dev/urandom, it blocks if the entropy pool has not yet been initialized. If the GRND_NONBLOCK flag is set, then getrandom() does not block in these cases, but instead immediately rai...
python.library.os#os.GRND_NONBLOCK
os.GRND_RANDOM If this bit is set, then random bytes are drawn from the /dev/random pool instead of the /dev/urandom pool. New in version 3.6.
python.library.os#os.GRND_RANDOM
os.initgroups(username, gid) Call the system initgroups() to initialize the group access list with all of the groups of which the specified username is a member, plus the specified group id. Availability: Unix. New in version 3.2.
python.library.os#os.initgroups
os.isatty(fd) Return True if the file descriptor fd is open and connected to a tty(-like) device, else False.
python.library.os#os.isatty
os.kill(pid, sig) Send signal sig to the process pid. Constants for the specific signals available on the host platform are defined in the signal module. Windows: The signal.CTRL_C_EVENT and signal.CTRL_BREAK_EVENT signals are special signals which can only be sent to console processes which share a common console wi...
python.library.os#os.kill
os.killpg(pgid, sig) Send the signal sig to the process group pgid. Raises an auditing event os.killpg with arguments pgid, sig. Availability: Unix.
python.library.os#os.killpg
os.lchflags(path, flags) Set the flags of path to the numeric flags, like chflags(), but do not follow symbolic links. As of Python 3.3, this is equivalent to os.chflags(path, flags, follow_symlinks=False). Raises an auditing event os.chflags with arguments path, flags. Availability: Unix. Changed in version 3.6: Ac...
python.library.os#os.lchflags
os.lchmod(path, mode) Change the mode of path to the numeric mode. If path is a symlink, this affects the symlink rather than the target. See the docs for chmod() for possible values of mode. As of Python 3.3, this is equivalent to os.chmod(path, mode, follow_symlinks=False). Raises an auditing event os.chmod with ar...
python.library.os#os.lchmod
os.lchown(path, uid, gid) Change the owner and group id of path to the numeric uid and gid. This function will not follow symbolic links. As of Python 3.3, this is equivalent to os.chown(path, uid, gid, follow_symlinks=False). Raises an auditing event os.chown with arguments path, uid, gid, dir_fd. Availability: Unix...
python.library.os#os.lchown
os.linesep The string used to separate (or, rather, terminate) lines on the current platform. This may be a single character, such as '\n' for POSIX, or multiple characters, for example, '\r\n' for Windows. Do not use os.linesep as a line terminator when writing files opened in text mode (the default); use a single '...
python.library.os#os.linesep
os.link(src, dst, *, src_dir_fd=None, dst_dir_fd=None, follow_symlinks=True) Create a hard link pointing to src named dst. This function can support specifying src_dir_fd and/or dst_dir_fd to supply paths relative to directory descriptors, and not following symlinks. Raises an auditing event os.link with arguments sr...
python.library.os#os.link
os.listdir(path='.') Return a list containing the names of the entries in the directory given by path. The list is in arbitrary order, and does not include the special entries '.' and '..' even if they are present in the directory. If a file is removed from or added to the directory during the call of this function, ...
python.library.os#os.listdir
os.listxattr(path=None, *, follow_symlinks=True) Return a list of the extended filesystem attributes on path. The attributes in the list are represented as strings decoded with the filesystem encoding. If path is None, listxattr() will examine the current directory. This function can support specifying a file descrip...
python.library.os#os.listxattr
os.lockf(fd, cmd, len) Apply, test or remove a POSIX lock on an open file descriptor. fd is an open file descriptor. cmd specifies the command to use - one of F_LOCK, F_TLOCK, F_ULOCK or F_TEST. len specifies the section of the file to lock. Raises an auditing event os.lockf with arguments fd, cmd, len. Availability:...
python.library.os#os.lockf
os.lseek(fd, pos, how) Set the current position of file descriptor fd to position pos, modified by how: SEEK_SET or 0 to set the position relative to the beginning of the file; SEEK_CUR or 1 to set it relative to the current position; SEEK_END or 2 to set it relative to the end of the file. Return the new cursor posi...
python.library.os#os.lseek
os.lstat(path, *, dir_fd=None) Perform the equivalent of an lstat() system call on the given path. Similar to stat(), but does not follow symbolic links. Return a stat_result object. On platforms that do not support symbolic links, this is an alias for stat(). As of Python 3.3, this is equivalent to os.stat(path, dir...
python.library.os#os.lstat
os.major(device) Extract the device major number from a raw device number (usually the st_dev or st_rdev field from stat).
python.library.os#os.major
os.makedev(major, minor) Compose a raw device number from the major and minor device numbers.
python.library.os#os.makedev
os.makedirs(name, mode=0o777, exist_ok=False) Recursive directory creation function. Like mkdir(), but makes all intermediate-level directories needed to contain the leaf directory. The mode parameter is passed to mkdir() for creating the leaf directory; see the mkdir() description for how it is interpreted. To set t...
python.library.os#os.makedirs
os.memfd_create(name[, flags=os.MFD_CLOEXEC]) Create an anonymous file and return a file descriptor that refers to it. flags must be one of the os.MFD_* constants available on the system (or a bitwise ORed combination of them). By default, the new file descriptor is non-inheritable. The name supplied in name is used ...
python.library.os#os.memfd_create
os.MFD_CLOEXEC os.MFD_ALLOW_SEALING os.MFD_HUGETLB os.MFD_HUGE_SHIFT os.MFD_HUGE_MASK os.MFD_HUGE_64KB os.MFD_HUGE_512KB os.MFD_HUGE_1MB os.MFD_HUGE_2MB os.MFD_HUGE_8MB os.MFD_HUGE_16MB os.MFD_HUGE_32MB os.MFD_HUGE_256MB os.MFD_HUGE_512MB os.MFD_HUGE_1GB os.MFD_HUGE_2GB os.MFD_HUGE_16GB ...
python.library.os#os.MFD_ALLOW_SEALING
os.MFD_CLOEXEC os.MFD_ALLOW_SEALING os.MFD_HUGETLB os.MFD_HUGE_SHIFT os.MFD_HUGE_MASK os.MFD_HUGE_64KB os.MFD_HUGE_512KB os.MFD_HUGE_1MB os.MFD_HUGE_2MB os.MFD_HUGE_8MB os.MFD_HUGE_16MB os.MFD_HUGE_32MB os.MFD_HUGE_256MB os.MFD_HUGE_512MB os.MFD_HUGE_1GB os.MFD_HUGE_2GB os.MFD_HUGE_16GB ...
python.library.os#os.MFD_CLOEXEC