From patchwork Wed May 30 01:15:01 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zack Weinberg X-Patchwork-Id: 27548 Received: (qmail 110540 invoked by alias); 30 May 2018 01:15:37 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 110251 invoked by uid 89); 30 May 2018 01:15:05 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-25.9 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, SPF_PASS autolearn=ham version=3.3.2 spammy=Concepts, concepts, loud, foreground X-HELO: mailbackend.panix.com From: Zack Weinberg To: libc-alpha@sourceware.org Subject: [PATCH] [manual] Job control is no longer optional. Date: Tue, 29 May 2018 21:15:01 -0400 Message-Id: <20180530011501.21432-1-zackw@panix.com> MIME-Version: 1.0 The manual contains an entire @node devoted to warning people that job control is an optional POSIX feature and might not be implemented in the kernel. Job control was made mandatory in POSIX.1-2001: compare with . Seventeen years later, it seems to me we do not need a warning this loud anymore. Instead there is a short note in the top-level "Job Control" node telling people that "old" systems might not support job control and there's the _POSIX_JOB_CONTROL macro if you really need it. OK? * manual/job.texi (Job Control is Optional): Remove node, as job control has not been optional in quite some time. (Job Control): Mention briefly that systems older than POSIX.1-2001 might not support job control. (setpgid): Remove cross-reference to deleted node. * manual/conf.texi (_POSIX_JOB_CONTROL): Will always be defined on systems conforming to POSIX.1-2001. --- manual/conf.texi | 2 ++ manual/job.texi | 38 +++++++++----------------------------- 2 files changed, 11 insertions(+), 29 deletions(-) diff --git a/manual/conf.texi b/manual/conf.texi index f1dce4aa44..51fb2f5aa1 100644 --- a/manual/conf.texi +++ b/manual/conf.texi @@ -156,6 +156,8 @@ supported; use @code{sysconf} to find out. @xref{Sysconf}. If this symbol is defined, it indicates that the system supports job control. Otherwise, the implementation behaves as if all processes within a session belong to a single process group. @xref{Job Control}. +Systems conforming to the 2001 revision of POSIX, or newer, will +always define this symbol. @end deftypevr @deftypevr Macro int _POSIX_SAVED_IDS diff --git a/manual/job.texi b/manual/job.texi index 944967a73d..e304313ca7 100644 --- a/manual/job.texi +++ b/manual/job.texi @@ -19,9 +19,15 @@ You need to be familiar with concepts relating to process creation Handling}) in order to understand this material presented in this chapter. +@vindex _POSIX_JOB_CONTROL +Some old systems do not support job control, but @gnusystems{} always +have, and it is a required feature in the 2001 revision of POSIX.1 +(@pxref{POSIX}). If you need to be portable to old systems, you can +use the @code{_POSIX_JOB_CONTROL} macro to test at compile-time +whether the system supports job control. @xref{System Options}. + @menu * Concepts of Job Control:: Jobs can be controlled by a shell. -* Job Control is Optional:: Not all POSIX systems support job control. * Controlling Terminal:: How a process gets its controlling terminal. * Access to the Terminal:: How processes share the controlling terminal. * Orphaned Process Groups:: Jobs left after the user logs out. @@ -29,7 +35,7 @@ chapter. * Functions for Job Control:: Functions to control process groups. @end menu -@node Concepts of Job Control, Job Control is Optional, , Job Control +@node Concepts of Job Control @section Concepts of Job Control @cindex shell @@ -102,30 +108,7 @@ jobs between foreground and background. @xref{Access to the Terminal}, for more information about I/O to the controlling terminal. -@node Job Control is Optional, Controlling Terminal, Concepts of Job Control , Job Control -@section Job Control is Optional -@cindex job control is optional - -Not all operating systems support job control. @gnusystems{} do -support job control, but if you are using @theglibc{} on some other -system, that system may not support job control itself. - -You can use the @code{_POSIX_JOB_CONTROL} macro to test at compile-time -whether the system supports job control. @xref{System Options}. - -If job control is not supported, then there can be only one process -group per session, which behaves as if it were always in the foreground. -The functions for creating additional process groups simply fail with -the error code @code{ENOSYS}. - -The macros naming the various job control signals (@pxref{Job Control -Signals}) are defined even if job control is not supported. However, -the system never generates these signals, and attempts to send a job -control signal or examine or specify their actions report errors or do -nothing. - - -@node Controlling Terminal, Access to the Terminal, Job Control is Optional, Job Control +@node Controlling Terminal @section Controlling Terminal of a Process One of the attributes of a process is its controlling terminal. Child @@ -1166,9 +1149,6 @@ The @code{setpgid} function puts the process @var{pid} into the process group @var{pgid}. As a special case, either @var{pid} or @var{pgid} can be zero to indicate the process ID of the calling process. -This function fails on a system that does not support job control. -@xref{Job Control is Optional}, for more information. - If the operation is successful, @code{setpgid} returns zero. Otherwise it returns @code{-1}. The following @code{errno} error conditions are defined for this function: