Catching errors in a shell scripts

[Simon Skogh]

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Matthew Flaschen wrote:
> Simon Skogh wrote:
>> Matthew Flaschen wrote:
>>> Simon Skogh wrote:
>>>> Matthew Flaschen wrote:
>>>>> I see.  That's because standard output and standard error
>>>>> are different streams, and `command` (incidentially I find
>>>>> the equivalent $(command) easier to type) apparently
>>>>> doesn't capture standard error.  The below works, but there
>>>>> may well be a less hackish way.  This is a demo for
>>>>> capturing the error from trying to copy a non-existent
>>>>> file.  For all commands, it will capture both error and
>>>>> output to alloutput: tempoutput=`mktemp` cp
>>>>> nonexistent_file backup &> tempoutput; alloutput=`cat
>>>>> tempoutput` rm $tempoutput; echo "All output: $alloutput"
>>>>> mktemp generates a random filename, which helps prevent
>>>>> shenanigans. Matt Flaschen
>>>> The simplicity of this has me wanting to beat my head with a
>>>> frying pan.
>>> My experience is, the simpler the problem, the less likely I
>>> can figure it out without help.  This one actually took me a
>>> few minutes, though. Matt Flaschen
>> Can't agree more. Now I'm just trying to beat sed into submission
>>  (we've never been on good terms) to make the output escape
>> single quotes, i.e. turn ' into \' so the queries won't break
>
> Like:
>
> matthew at e1505-laptop:~/Code/Shell% echo "test='boo'">test.txt
> matthew at e1505-laptop:~/Code/Shell% sed -i "s/'/\\\\'/g" test.txt
> matthew at e1505-laptop:~/Code/Shell% cat test.txt test=\'boo\'
>
> ?  I have no idea why you need that many backslashes (probably the
> shell is also processing it), but it seems to work. :)
>
> Matt Flaschen
>
Damnit, I only went to three slashes, haha.

Thanks for all the help, Matt!


Simon
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