[Discuss] segfault with cygwin

[John Blomfield]

pw wrote:
> John Blomfield wrote:
>>>       2 [main] sh 1780 _cygtls::handle_exceptions: Error while 
>>> dumping state (probably corrupted stack)
>>> Segmentation fault (core dumped)
>>>
>> I don't know anything about cygwin but this appears to be an 
>> exception error "thrown" by the program due to trying to access a 
>> part of memory that is not defined.  Usually happens when you exceed 
>> the bounds of a defined memory area e.g. an array of bytes or refer 
>> to an address that is not allocated.  Probably a bug in cygwin or you 
>> have written something in bash script that writes stuff where you 
>> shouldn't.
>>
>> John Blomfield
>>
>
> I'm not sure how I am writing to memory that I shouldn't.
> I'm using all the standard tools; sed, awk, cut, sort...
>
> There's no custom code or programs just bash stuff.
>
> I was thinking that it could be a memory leak in
> one of the bash utilities.
>
I don't think its a memory "leak", which usually means that you allocate 
more and more memory without deleting unused memory, since that usually 
just slows execution down as more and more virtual memory on hard drive 
is used.  Segmentation errors occur when you try to step outside the 
address space allocated to your process, Linux stops you doing this, 
catches the error and throws an exception.  Unlike some OS's which used 
to allow you to overwrite program space or system areas and crash the 
whole system.

John
> For example, the script iterates through all the lines (430 lines)
> in each file and selects only a few columns from each line
> (using 'cut'). The script also uses awk to detect an unwanted value
> in one field and then excludes that line from the output.
>
> There are 156 files in all so if the script reads something like:
>
>
> for FILE in `cat file_list.txt`;do
>     OUT_FILE=`echo $FILE| awk '{print $0 ".out"}'`;
>     for LINE in `cat $FILE| sed -e "s/\"//g"| cut -d "|" -f 
> 2,4,7,9,10,11,12,13`;do
>         ALARM=`echo $LINE| awk -F "|" '{print $3}'`
>         if [ "$ALARM" != "gotcha" ]; then
>             echo $LINE >> $OUT_FILE;
>         fi
>     done
> done
>
>
> I wonder how much memory gets used due to bash
> doing everything in memory before actually
> outputting anything....
>
> Peter
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