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Diffstat (limited to 'man2/getpid.2')
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diff --git a/man2/getpid.2 b/man2/getpid.2 deleted file mode 100644 index 811270f05..000000000 --- a/man2/getpid.2 +++ /dev/null @@ -1,150 +0,0 @@ -.\" Copyright 1993 Rickard E. Faith (faith@cs.unc.edu) -.\" -.\" SPDX-License-Identifier: Linux-man-pages-copyleft -.\" -.TH getpid 2 (date) "Linux man-pages (unreleased)" -.SH NAME -getpid, getppid \- get process identification -.SH LIBRARY -Standard C library -.RI ( libc ", " \-lc ) -.SH SYNOPSIS -.nf -.B #include <unistd.h> -.P -.B pid_t getpid(void); -.B pid_t getppid(void); -.fi -.SH DESCRIPTION -.BR getpid () -returns the process ID (PID) of the calling process. -(This is often used by -routines that generate unique temporary filenames.) -.P -.BR getppid () -returns the process ID of the parent of the calling process. -This will be either the ID of the process that created this process using -.BR fork (), -or, if that process has already terminated, -the ID of the process to which this process has been reparented (either -.BR init (1) -or a "subreaper" process defined via the -.BR prctl (2) -.B PR_SET_CHILD_SUBREAPER -operation). -.SH ERRORS -These functions are always successful. -.SH VERSIONS -On Alpha, instead of a pair of -.BR getpid () -and -.BR getppid () -system calls, a single -.BR getxpid () -system call is provided, which returns a pair of PID and parent PID. -The glibc -.BR getpid () -and -.BR getppid () -wrapper functions transparently deal with this. -See -.BR syscall (2) -for details regarding register mapping. -.SH STANDARDS -POSIX.1-2008. -.SH HISTORY -POSIX.1-2001, 4.3BSD, SVr4. -.SS C library/kernel differences -From glibc 2.3.4 up to and including glibc 2.24, -the glibc wrapper function for -.BR getpid () -cached PIDs, -with the goal of avoiding additional system calls when a process calls -.BR getpid () -repeatedly. -Normally this caching was invisible, -but its correct operation relied on support in the wrapper functions for -.BR fork (2), -.BR vfork (2), -and -.BR clone (2): -if an application bypassed the glibc wrappers for these system calls by using -.BR syscall (2), -then a call to -.BR getpid () -in the child would return the wrong value -(to be precise: it would return the PID of the parent process). -.\" The following program demonstrates this "feature": -.\" -.\" #define _GNU_SOURCE -.\" #include <sys/syscall.h> -.\" #include <sys/wait.h> -.\" #include <stdint.h> -.\" #include <stdio.h> -.\" #include <stdlib.h> -.\" #include <unistd.h> -.\" -.\" int -.\" main(int argc, char *argv[]) -.\" { -.\" /* The following statement fills the getpid() cache */ -.\" -.\" printf("parent PID = %ld\n", (intmax_t) getpid()); -.\" -.\" if (syscall(SYS_fork) == 0) { -.\" if (getpid() != syscall(SYS_getpid)) -.\" printf("child getpid() mismatch: getpid()=%jd; " -.\" "syscall(SYS_getpid)=%ld\n", -.\" (intmax_t) getpid(), (long) syscall(SYS_getpid)); -.\" exit(EXIT_SUCCESS); -.\" } -.\" wait(NULL); -.\"} -In addition, there were cases where -.BR getpid () -could return the wrong value even when invoking -.BR clone (2) -via the glibc wrapper function. -(For a discussion of one such case, see BUGS in -.BR clone (2).) -Furthermore, the complexity of the caching code had been -the source of a few bugs within glibc over the years. -.P -Because of the aforementioned problems, -since glibc 2.25, the PID cache is removed: -.\" commit c579f48edba88380635ab98cb612030e3ed8691e -.\" https://sourceware.org/glibc/wiki/Release/2.25#pid_cache_removal -calls to -.BR getpid () -always invoke the actual system call, rather than returning a cached value. -.\" FIXME . -.\" Review progress of https://bugzilla.redhat.com/show_bug.cgi?id=1469757 -.SH NOTES -If the caller's parent is in a different PID namespace (see -.BR pid_namespaces (7)), -.BR getppid () -returns 0. -.P -From a kernel perspective, -the PID (which is shared by all of the threads in a multithreaded process) -is sometimes also known as the thread group ID (TGID). -This contrasts with the kernel thread ID (TID), -which is unique for each thread. -For further details, see -.BR gettid (2) -and the discussion of the -.B CLONE_THREAD -flag in -.BR clone (2). -.SH SEE ALSO -.BR clone (2), -.BR fork (2), -.BR gettid (2), -.BR kill (2), -.BR exec (3), -.BR mkstemp (3), -.BR tempnam (3), -.BR tmpfile (3), -.BR tmpnam (3), -.BR credentials (7), -.BR pid_namespaces (7) |