attach: ptrace(PTRACE_ATTACH, …): Operation not permitted
Cause:
The error is common because strace process is already running in the background
[oracle@exdbadm01 ~]$ strace -rp 6307 -o lb.trc
attach: ptrace(PTRACE_ATTACH, ...): Operation not permitted
Workaround:
Check the existing strace process using ps and note the pid
[root@exdbadm01 oracle]# ps aux | grep "strace"
oracle 6879 0.0 0.0 4140 640 pts/1 T 01:11 0:00 strace -rp 6307
Kill the process using process id
[root@exdbadm01 oracle]# kill -9 6879
Strace works fine now
[root@exdbadm01 oracle]# strace -rp 6307 -o lb.trc
Process 6307 attached - interrupt to quit