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| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2006-03-20 06:33:14 +0000 |
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| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2006-03-20 06:33:14 +0000 |
| commit | f4cb7bd37e817f92dce76115d95b8c6a2f0601bf (patch) | |
| tree | 6ece6e3300621e5722d1e12358cd713df27565fa | |
| parent | c3742154c19aa673d9b1125e6b2d4fb0daa45b6a (diff) | |
| download | man-pages-f4cb7bd37e817f92dce76115d95b8c6a2f0601bf.tar.gz | |
Not yet ready for 2.26.
| -rw-r--r-- | man2/unshare.2 | 163 |
1 files changed, 0 insertions, 163 deletions
diff --git a/man2/unshare.2 b/man2/unshare.2 deleted file mode 100644 index 00fe3f3d83..0000000000 --- a/man2/unshare.2 +++ /dev/null @@ -1,163 +0,0 @@ -.\" (C) 2006, Janak Desai <janak@us.ibm.com> -.\" (C) 2006, Michael Kerrisk <mtk-manpages@gmx.ne> -.\" Licensed under the GPL -.\" -.TH UNSHARE 2 2005-03-10 "Linux 2.6.16" "Linux Programmer's Manual" -.SH NAME -unshare \- disassociate parts of the process execution context -.SH SYNOPSIS -.nf -.B #include <sched.h> -.sp -.BI "int unshare(int " flags ); -.fi -.SH DESCRIPTION -.BR unshare () -allows a process to disassociate parts of its execution -context that are currently being shared with other processes. -Part of the execution context, such as the namespace, is shared -implicitly when a new process is created using -.BR fork (2) -or -.BR vfork (2), -while other parts, such as virtual memory, may be -shared by explicit request when creating a process using -.BR clone (2). - -The main use of -.BR unshare () -is to allow a process to control its -shared execution context without creating a new process. - -The -.I flags -argument is a bit mask that specifies which parts of -the execution context should be unshared. -This argument is specified by ORing together zero or more -of the following constants: -.TP -.B CLONE_FILES -Reverse the effect of the -.BR clone (2) -.B CLONE_FILES -flag. -Unshare the file descriptor table, so that the calling process -no longer shares its file descriptors with any other process. -.TP -.B CLONE_FS -Reverse the effect of the -.BR clone (2) -.B CLONE_FS -flag. -Unshare file system attributes, so that the calling process -no longer shares its root directory, current directory, -or umask attributes with any other process. -.BR chroot (2), -.BR chdir (2), -or -.BR umask (2) -.TP -.B CLONE_NEWNS -.\" These flag name are inconsistent: -.\" CLONE_NEWNS does the same thing in clone(), but CLONE_VM, -.\" CLONE_FS, and CLONE_FILES reverse the action of the clone() -.\" flags of the same name. -This flag has the same effect as the -.BR clone (2) -.B CLONE_NEWNS -flag. -Unshare the namespace, so that the calling process has a private copy of -its namespace which is not shared with any other process. -Specifying this flag automatically implies -.B CLONE_FS -as well. -.\" As at 2.6.16, the following forced implications also apply, -.\" although CLONE_THREAD and CLONE_SIGHAND are not yet implemented. -.\" If CLONE_THREAD is set force CLONE_VM. -.\" If CLONE_VM is set, force CLONE_SIGHAND. -.\" If CLONE_SIGHAND is set and signals are also being shared -.\" (i.e., current->signal->count > 1), force CLONE_THREAD. -.TP -.B CLONE_VM -Reverse the effect of the -.BR clone (2) -.B CLONE_VM -flag. -.RB ( CLONE_VM -is also implicitly set by -.BR vfork (2), -and can be reversed using this -.BR unshare () -flag.) -Unshare virtual memory, so that the calling process no -longer shares its virtual address space with any other process. -.PP -If -.I flags -is specified as zero, then -.BR unshare () -is a no-op; -no changes are made to the calling process's execution context. -.SH RETURN VALUE -On success, zero returned. On failure, \-1 is returned and -.I errno -is set to indicate the error. -.SH ERRORS -.TP -.B EPERM -.I flags -specified -.B CLONE_NEWNS -but the calling process was not privileged (did not have the -.B CAP_SYS_ADMIN -capability). -.TP -.B ENOMEM -Cannot allocate sufficient memory to copy parts of caller's -context that need to be unshared. -.TP -.B EINVAL -An invalid bit was specified in -.IR flags . -.SH CONFORMING TO -The -.BR unshare () -system call is Linux-specific. -.SH NOTES -The -.BR unshare () -system call was added to Linux in kernel 2.6.16. - -Not all of the process attributes that can be shared when -a new process is created using -.BR clone (2) -can be unshared using -.BR unshare (). -In particular, as at kernel 2.6.16, -.BR unshare () -does not implement flags that reverse the effects of -.BR CLONE_SIGHAND , -.\" However we can do unshare(CLONE_SIGHAND) if CLONE_SIGHAND -.\" was not specified when doing clone(); i.e., unsharing -.\" signal handlers is permitted if we are not actually -.\" sharing signal handlers. mtk -.BR CLONE_SYSVSEM , -or -.BR CLONE_THREAD . -Such functionality may be added in the future, if required. -.\" -.\"9) Future Work -.\"-------------- -.\"The current implementation of unshare does not allow unsharing of -.\"signals and signal handlers. Signals are complex to begin with and -.\"to unshare signals and/or signal handlers of a currently running -.\"process is even more complex. If in the future there is a specific -.\"need to allow unsharing of signals and/or signal handlers, it can -.\"be incrementally added to unshare without affecting legacy -.\"applications using unshare. -.\" -.SH SEE ALSO -.BR clone (2), -.BR fork (2), -.BR vfork (2), -Documentation/unshare.txt |