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<p>2> starts a new file. 2>> appends to an existing file
(and creates it if need be). Since the pipe is a single operation
for the purpose of STDERR redirection, 2> ensures that the file
is empty when first written to.</p>
<p>I suppose you could call a function after the pipe with
redirection, passing it the exit status ($?) and error file
(/tmp/pipe-$$.err). If the function returns, then things were OK.
Something bad causes function to exit script with error code.</p>
<p>Leonard</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 7/22/2023 7:22 PM, John Carlson
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAGC3UE=eeuPFFEm9jb+kiLiYCs-KiPoP5QD0XiV5KcJWEwXxJg@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="auto">Thanks Leonard, i was hoping to use a function
because i have a whole list of pipelines to run in my script.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Something like:</div>
<div dir="auto"><br>
</div>
<div dir="auto">catcher “oops” (sed ‘s/ //‘ | tr “\n” “ “ | ….)</div>
<div dir="auto">catcher…</div>
<div dir="auto"><br>
</div>
<div dir="auto">I don’t want a script for catcher. If a function
won’t suffice, a preprocessor will.</div>
<div dir="auto"><br>
</div>
<div dir="auto">You probably want 2>> instead of 2> but
I’m willing to hear your reasoning.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Thanks for your help!</div>
<div><br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sat, Jul 22, 2023 at 9:01
PM Leonard Daly <<a
href="mailto:Leonard.Daly@realism.com"
moz-do-not-send="true" class="moz-txt-link-freetext">Leonard.Daly@realism.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)">
<div>
<p>Not sure why you would want a script as this is almost
always done in-line.</p>
<p>$? contains the exit status. 0 is almost always success
(I don't know where it is not) and != 0 is failure.
Error message is written to STDERR unless you direct a
command to fail silently.</p>
<p>So something like<br>
</p>
<pre style="font-family:monospace"><font style="font-family:monospace;color:rgb(0,0,0)" face="monospace">(A | B | C ...) 2> /tmp/pipe-$$.err
if [ $? -ne 0 ]
then
exitCode=$?
cat /tmp/pipe-$$.err
exit $exitCode
fi</font></pre>
<p>Passing the piped command to a function can be
dangerous/difficult because of shell interpolation and
quoting. Also note that the piped output (STDOUT) is
printed on the default (at the time of the pipe) output
(probably console), and pipe-$$.err is never cleaned up
(deleted). That is not really bad because most systems
delete files after 24-48 hours in /tmp. If there are no
errors, then /tmp/pipe-$$.err is never created.<br>
</p>
<p>Additional useful info:
<a
href="https://unix.stackexchange.com/questions/164482/pipe-redirect-a-group-of-commands"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">https://unix.stackexchange.com/questions/164482/pipe-redirect-a-group-of-commands</a></p>
<p>Leonard Daly<br>
</p>
</div>
<div>
<p><br>
</p>
<p><br>
</p>
<div>On 7/21/2023 10:15 PM, John Carlson wrote:<br>
</div>
</div>
<div>
<blockquote type="cite"> Linux folks:
<div dir="auto"><br>
</div>
<div dir="auto">Does anyone have a bash function (not a
separate script) to check the exit status of the
passed in pipeline or passed in exit status, print
out the passed in error message, and exit the script
if the exit status indicates failure?</div>
<div dir="auto"><br>
</div>
<div dir="auto">Thanks!</div>
<div dir="auto"><br>
</div>
<div dir="auto">Should be fairly easy to write?</div>
<div dir="auto"><br>
</div>
<div dir="auto">John </div>
<br>
<fieldset></fieldset>
</blockquote>
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<blockquote type="cite">
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<div>
<blockquote type="cite"> </blockquote>
<div>-- <br>
<b>Leonard Daly</b><br>
3D Systems Engineering<br>
President, Daly Realism - <i>Creating the Future</i><br>
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<div class="moz-signature">-- <br>
<b>Leonard Daly</b><br>
3D Systems Engineering<br>
President, Daly Realism - <i>Creating the Future</i><br>
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