tracing of system calls on Linux

[Nate Eldredge]

Partha Saha writes:
 > Hi,
 > 
 > I assume that strace works on Linux by using the
 > /proc filesystem.  

Not true.  /proc on linux has no such capability.  strace uses the
ptrace(2) system call.

 > If started by a command line argument
 > such as "-e write" where I indicate interest in only
 > the write system calls, I am wondering whether traps
 > are generated from _all_ system calls and then logging
 > done after filtering over whichever system calls I have expressed
 > interest in,

That's correct.

 > or whether traps are generated only from
 > those system calls I have indicated after the "-e" option.

No, ptrace does not provide this facility.

 > The second method will be obviously more efficient but I
 > am not sure whether the /proc filesystem allows it.
 > 
 > Thanks,
 > 
 > Partha Saha
 > 
 > 
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-- 

Nate Eldredge
neldredge at hmc.edu