os.setpgrp() Call the system call setpgrp() or setpgrp(0, 0) depending on which version is implemented (if any). See the Unix manual for the semantics. Availability: Unix.

os.setpgid(pid, pgrp) Call the system call setpgid() to set the process group id of the process with id pid to the process group with id pgrp. See the Unix manual for the semantics. Availability: Unix.

os.setgroups(groups) Set the list of supplemental group ids associated with the current process to groups. groups must be a sequence, and each element must be an integer identifying a group. This operation is typically available only to the superuser. Availability: Unix. Note On Mac OS X, the length of groups may not exceed the system-defined maximum number of effective group ids, typically 16. See the documentation for getgroups() for cases where it may not return the same group list set b

os.setgid(gid) Set the current process’ group id. Availability: Unix.

os.seteuid(euid) Set the current process’s effective user id. Availability: Unix.

os.setegid(egid) Set the current process’s effective group id. Availability: Unix.

os.sep The character used by the operating system to separate pathname components. This is '/' for POSIX and '\\' for Windows. Note that knowing this is not sufficient to be able to parse or concatenate pathnames — use os.path.split() and os.path.join() — but it is occasionally useful. Also available via os.path.

os.sendfile(out, in, offset, count) os.sendfile(out, in, offset, count, [headers, ][trailers, ]flags=0) Copy count bytes from file descriptor in to file descriptor out starting at offset. Return the number of bytes sent. When EOF is reached return 0. The first function notation is supported by all platforms that define sendfile(). On Linux, if offset is given as None, the bytes are read from the current position of in and the position of in is updated. The second case may be used on Mac OS X

os.sched_yield() Voluntarily relinquish the CPU.

os.sched_setscheduler(pid, policy, param) Set the scheduling policy for the process with PID pid. A pid of 0 means the calling process. policy is one of the scheduling policy constants above. param is a sched_param instance.