LSOF

The lsof command is to list open files

You can use it to:

List all process which has opened a file:
```
$ lsof ./cron/script.sh
```
List all opened files by a user:
```
$ lsof -u markgono
```
List all opened files by port:
```
$ lsof -i:3000
```

Using this information:

$ lsof -i:8000
COMMAND  PID     USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
node    8528 markgono   51u  IPv4 0x78fb118ce8927df5      0t0  TCP localhost:irdmi (LISTEN)

You can do something with the process information, like:

List all files which have been opened by that process:

$ lsof ./script.sh
…
node    8532 markgono   21r     CHR                3,2      0t0        311 /dev/null
node    8532 markgono   22u     CHR               16,1      0t0        653 /dev/ttys001
node    8532 markgono   23u     CHR               16,1      0t0        653 /dev/ttys001

Kill the process:
```
$ kill -9 8528
```