No pipefail option?

No pipefail option?

[Shawn Halpenny]

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It seems like it would be a good bash-compatibility option to have
available.  I know we can check $pipestatus, but often I simply want to
abort the script if any command in the pipeline failed without having to do
an explicit check (similarly to how the errexit option works).  Explicit
checks too easily get forgotten or overlooked or even just implemented
incorrectly.

--Shawn

Re: No pipefail option?

[Peter Stephenson]

On Fri, 4 Oct 2013 08:59:49 -0700
Shawn Halpenny <paxunix@gmail.com> wrote:
> It seems like it would be a good bash-compatibility option to have
> available.  I know we can check $pipestatus, but often I simply want to
> abort the script if any command in the pipeline failed without having to do
> an explicit check (similarly to how the errexit option works).  Explicit
> checks too easily get forgotten or overlooked or even just implemented
> incorrectly.

It's not impossible it's this simple.

Indeed, if $pipestatus is working as advertised, it really ought to be
this simple...

diff --git a/Doc/Zsh/options.yo b/Doc/Zsh/options.yo
index ec86232..71bddd5 100644
--- a/Doc/Zsh/options.yo
+++ b/Doc/Zsh/options.yo
@@ -1683,6 +1683,20 @@ Sequences of digits indicating a numeric base such as the `tt(08)'
 component in `tt(08#77)' are always interpreted as decimal, regardless
 of leading zeroes.
 )
+pindex(PIPE_FAIL)
+pindex(NO_PIPE_FAIL)
+pindex(PIPEFAIL)
+pindex(NOPIPEFAIL)
+cindex(exit status from pipeline)
+cindex(status, on exit from pipeline)
+cindex(pipeline, exit status from)
+itme(tt(PIPE_FAIL))(
+By default, when a pipeline exits the exit status recorded by the shell
+and returned by the shell variable tt($?) reflects that of the
+rightmost element of a pipeline.  If this option is set, the exit status
+instead reflects the status of the rightmost element of the pipeline
+that was non-zero, or zero if all elements exited with zero status.
+)
 pindex(SOURCE_TRACE)
 pindex(NO_SOURCE_TRACE)
 pindex(SOURCETRACE)
diff --git a/Src/jobs.c b/Src/jobs.c
index e1b24b2..b9d7a84 100644
--- a/Src/jobs.c
+++ b/Src/jobs.c
@@ -508,15 +508,22 @@ update_job(Job jn)
     jn->stat |= (somestopped) ? STAT_CHANGED | STAT_STOPPED :
 	STAT_CHANGED | STAT_DONE;
     if (job == thisjob && (jn->stat & STAT_DONE)) {
-	int i;
+	int i, newlastval = 0;
 	Process p;
 
-	for (p = jn->procs, i = 0; p && i < MAX_PIPESTATS; p = p->next, i++)
+	for (p = jn->procs, i = 0; p && i < MAX_PIPESTATS; p = p->next, i++) {
 	    pipestats[i] = ((WIFSIGNALED(p->status)) ?
 			    0200 | WTERMSIG(p->status) :
 			    WEXITSTATUS(p->status));
-	if ((jn->stat & STAT_CURSH) && i < MAX_PIPESTATS)
+	    if (pipestats[i])
+		newlastval = pipestats[i];
+	}
+	if ((jn->stat & STAT_CURSH) && i < MAX_PIPESTATS) {
 	    pipestats[i++] = lastval;
+	    if (!lastval && isset(PIPEFAIL))
+		lastval = newlastval;
+	} else if (isset(PIPEFAIL))
+	    lastval= newlastval;
 	numpipestats = i;
     }
     if (!inforeground &&
diff --git a/Src/options.c b/Src/options.c
index ad869b2..ce73d99 100644
--- a/Src/options.c
+++ b/Src/options.c
@@ -205,6 +205,7 @@ static struct optname optns[] = {
 {{NULL, "overstrike",	      0},			 OVERSTRIKE},
 {{NULL, "pathdirs",	      OPT_EMULATE},		 PATHDIRS},
 {{NULL, "pathscript",	      OPT_EMULATE|OPT_BOURNE},	 PATHSCRIPT},
+{{NULL, "pipefail",           OPT_EMULATE},              PIPEFAIL},
 {{NULL, "posixaliases",       OPT_EMULATE|OPT_BOURNE},	 POSIXALIASES},
 {{NULL, "posixbuiltins",      OPT_EMULATE|OPT_BOURNE},	 POSIXBUILTINS},
 {{NULL, "posixcd",            OPT_EMULATE|OPT_BOURNE},	 POSIXCD},
diff --git a/Src/zsh.h b/Src/zsh.h
index e6f0f65..a46898d 100644
--- a/Src/zsh.h
+++ b/Src/zsh.h
@@ -2121,6 +2121,7 @@ enum {
     OVERSTRIKE,
     PATHDIRS,
     PATHSCRIPT,
+    PIPEFAIL,
     POSIXALIASES,
     POSIXBUILTINS,
     POSIXCD,
diff --git a/Test/E01options.ztst b/Test/E01options.ztst
index bcb34c3..e00eb0e 100644
--- a/Test/E01options.ztst
+++ b/Test/E01options.ztst
@@ -1096,3 +1096,18 @@
 0:IGNORE_CLOSE_BRACES option
 >this is OK
 >6
+
+  (setopt pipefail
+  true | true | true
+  print $?
+  true | false | true
+  print $?
+  exit 2 | false | true
+  print $?
+  false | exit 2 | true
+  print $?)
+0:PIPE_FAIL option
+>0
+>1
+>1
+>2

-- 
Peter Stephenson <p.w.stephenson@ntlworld.com>
Web page now at http://homepage.ntlworld.com/p.w.stephenson/