Possible solution:
strace -e trace=file sleep 1 2>&1 | grep -v "= -1 ENOENT"> strace.logstrace by default prints to stderr so redirect it to stdout.
Possible solution:
strace -e trace=file sleep 1 2>&1 | grep -v "= -1 ENOENT"> strace.logstrace by default prints to stderr so redirect it to stdout.