I am simply running a tail -n1 command 2>/dev/null and the output for some strange reason is showing me two different things:
> masscan_progress
=> "rate: 0.00-kpps, 0.00% done,3586348854:03:28 remaining, found=0 \rrate: 3.49-kpps, 0.08% done, 2:07:20 remaining, found=3 \rrate: 3.48-kpps, 0.16% done, 1:02:57 remaining, found=6 \rrate: 3.49-kpps, 0.24% done, 0:42:18 remaining, found=10 \rrate: 3.49-kpps, 0.31% done, 0:31:58 remaining, found=14 \rrate: 3.49-kpps, 0.40% done, 0:24:59 remaining, found=20 \rrate: 3.49-kpps, 0.47% done, 0:21:15 remaining, found=23 \rrate: 3.49-kpps, 0.55% done, 0:18:05 remaining, found=30 \rrate: 3.48-kpps, 0.63% done, 0:15:53 remaining, found=35 \rrate: 3.49-kpps, 0.71% done, 0:15:50 remaining, found=36 \rrate: 3.49-kpps, 0.78% done, 0:15:58 remaining, found=40 \rrate: 3.48-kpps, 0.87% done, 0:15:44 remaining, found=42 \rrate: 3.49-kpps, 0.94% done, 0:15:52 remaining, found=42 \rrate: 3.48-kpps, 1.02% done, 0:15:54 remaining, found=48 \rrate: 3.48-kpps, 1.09% done, 0:15:53 remaining, found=50 \rrate: 3.47-kpps, 1.18% done, 0:15:43 remaining, found=52 \rrate: 3.48-kpps, 1.25% done, 0:15:52 remaining, found=57 \rrate: ...
but puts returns exactly what I’m looking for:
> puts masscan_progress
rate: 3.47-kpps, 85.98% done, 0:02:15 remaining, found=3305
As a result, additional commands that searches data from the masscan_progress variable doesn’t see what I see in puts, but instead it sees the larger output.
I have actually never, ever seen this before and not quite sure why this is happening. Any pointers would be greatly appreciated.
>Solution :
"\r" (the escape representing a single carriage return character) tells the terminal to return to the start of the same line; output after that will overwrite what was written on that line before.