Hi guys,

When I compile and link my code on my gentoo box everything works fine and the program runs fine.
At work I have a ubuntu box and I need to run the same code, when I compile and link it everything seems fine; however, when I start it I get a segmentation fault. I use gfortran and upon checking with gdb I get:

(gdb) bt
#0 0xb7d94b6a in memcpy () from /lib/tls/i686/cmov/libc.so.6
#1 0xb7f4a653 in *_gfortrani_write_a (dtp=0xbf98d558, f=0x9f6f59c,
source=0xbf98d688 'Hello \000', len=8) at /usr/include/bits/string3.h:52
#2 0xb7f42cb8 in formatted_transfer_scalar (dtp=0xbf98d558,
type=<error reading variable>, p=0xbf98d688, len=8, size=8)
at ../../../src/libgfortran/io/transfer.c:1041
#3 0xb7f4305e in formatted_transfer (dtp=0xbf98d558,
type=<error reading variable>, p=0xbf98d688, kind=8, size=8, nelems=1)
at ../../../src/libgfortran/io/transfer.c:1378
#4 0xb7f3f396 in *_gfortran_transfer_character (dtp=0x2, p=0x20f6d515, len=5)
at ../../../src/libgfortran/io/transfer.c:1434
#5 0x0804894b in simple () at simple.f:12
#6 0x080489d9 in main ()
#7 0xb7d32685 in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
#8 0x08048701 in _start ()

Any idea on how I can fix this? Maybe something wrong with libc? By the way, I couldnt figure out how to include libc symbols for debuging in ubuntu.

Any help is highly appreciated.

Thanks in advance.

Efo

It's not always possible for the system to detect an array boundary crossing through segmentation faults. Sometimes it just goes ahead silently.

At first glance I would say that on gentoo it worked just because you were lucky but the problem is still there.

Can you post the guilty code?

Thanks irey,

I simplified the problem and I found:
1) The problem occurs only when out.txt is new (i.e. not there)
2) The problem disappears when I uncomment the second "rewind(7)"
3) The problem disappears if I remove "1x," from the format at 20

What basic mistake am I making?
Here is the code:

program simple
character*8 strngw,strngr
strngw='Hello'

open(unit=7,file='out.txt',status='unknown')
rewind(7)
read(7,20,end=10) strngr
10 continue
c rewind(7)
write(7,20) strngw
close(7)
20 format(1x,a5)
c
return
c
end program simple