Linux: Find All File Descriptors Used By a Process

To find all the file descriptors used by a process in Linux, you can use the "lsof" command.

The "lsof" command lists the open files for a process, including file descriptors. To list the file descriptors for a specific process, you can use the "-p" option followed by the process ID.

For example, to list the file descriptors for a process with a process ID of 12345, you can use the following command:

lsof -p 12345

This will display a list of all the open files for the process, including the file descriptor, file type, and file name.

For example, the output might look like this:

COMMAND   PID USER   FD   TYPE DEVICE SIZE/OFF   NODE NAME
process  12345 john  cwd    DIR   8,1     4096   1234 /home/john/process
process  12345 john  rtd    DIR   8,1     4096 212345 /
process  12345 john  txt    REG   8,1   231456 123456 /usr/bin/process
process  12345 john  mem    REG   8,1    16384 123457 /lib/libc-2.27.so
process  12345 john  mem    REG   8,1   131072 123458 /lib/ld-2.27.so

This shows the file descriptor, file type, and file name for each open file for the process with a process ID of 12345.

You can also use the "-a" option to display all open files, regardless of the process. For example:

lsof -a

This will display a list of all open files on the system, including the process ID, file descriptor, file type, and file name.

Note: The "lsof" command must be run with root privileges to list the file descriptors for all processes.