Each line in the trace contains the system call name, followed by its arguments in parentheses and its return value.
Run strace against /bin/foo and capture its output to a text file in output.txt:
$ strace -o output.txt /bin/foo
You can strace the webserver process and see what it's doing. For example, strace php5 fastcgi process, enter:
$ strace -p 22254 -s 80 -o /tmp/debug.lighttpd.txt
To see only a trace of the open, read system calls, enter :
$ strace -e trace=open,read -p 22254 -s 80 -o debug.webserver.txt
- -o filename : Write the trace output to the file filename rather than to screen (stderr).
- -p PID : Attach to the process with the process ID pid and begin tracing. The trace may be terminated at any time by a keyboard interrupt signal (hit CTRL-C). strace will respond by detaching itself from the traced process(es) leaving it (them) to continue running. Multiple -p options can be used to attach to up to 32 processes in addition to command (which is optional if at least one -p option is given).
- -s SIZE : Specify the maximum string size to print (the default is 32).
$ man strace
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