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What's the difference between Segmentation fault and Bus error and Illegal...?

 
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# 1  
Old 03-28-2008
Question What's the difference between Segmentation fault and Bus error and Illegal...?
What's the difference between Segmentation fault and Bus error and Illegal instruction?

Sometimes I got the one, and sometimes i got another, what are their differences?

Segmentation fault (core dump)?

Bus error (core dump)?

Illegal instruction (core dump)


Thanks


Daniel
# 2  
Old 03-28-2008
Segmentation Fault (also known as SIGSEGV and is usually signal 11) - You can get this message when the program tries to write/read outside the memory allocated for it or when writing memory which can only be read

Bus Error (also known as SIGBUS and is usually signal 10) - You can encounter this signal error when an invalid pointer is dereferenced i.e when you try to dereference an uninitialised pointer. It is similar to SIGSEGV but the difference is that SIGSEGV indicates an invalid access to valid memory, while SIGBUS indicates an access to an invalid address.

Illegal Instructions (also known as SIGILL and is usually signal 4) - This usually means that your program is trying to execute garbage or a privileged instruction. You might encounter this -
(a.) when you try to execute data
(b.) when you try to execute a corrupted executed file.
(c.) stack overflows
(d.) when the system has trouble running the handler for a signal

HTH
# 3  
Old 03-28-2008
Quote:
Originally Posted by ajitabhpandey
Segmentation Fault (also known as SIGSEGV and is usually signal 11) - You can get this message when the program tries to write/read outside the memory allocated for it or when writing memory which can only be read

Bus Error (also known as SIGBUS and is usually signal 10) - You can encounter this signal error when an invalid pointer is dereferenced i.e when you try to dereference an uninitialised pointer. It is similar to SIGSEGV but the difference is that SIGSEGV indicates an invalid access to valid memory, while SIGBUS indicates an access to an invalid address.

Illegal Instructions (also known as SIGILL and is usually signal 4) - This usually means that your program is trying to execute garbage or a privileged instruction. You might encounter this -
(a.) when you try to execute data
(b.) when you try to execute a corrupted executed file.
(c.) stack overflows
(d.) when the system has trouble running the handler for a signal

HTH
Thank you, HTHSmilie

I wonder is there any good book on unix or linux debugging?
Could anybody recommend one?

Daniel
 
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