LSA_03_homework_all_open_files_from_proc

#!/bin/bash

# List all opened files using only the /proc fs.
main() {
  pids | file_descriptor_folder | xargs ls -l | remove_ls_total_lines | remove_ls_file_attributes | remove_non_files | less
}

pids() {
  # we try all pids from 1 to the pid max and echo out the valid ones
  for P in $(seq 1 $(cat /proc/sys/kernel/pid_max)); do
   [ -d "/proc/$P" ] || continue
   echo $P
  done
}

file_descriptor_folder() {
  # we build the folder name for the file descriptors for each pid
  sed -r 's/(.*)/\/proc\/\1\/fd/'
}

remove_ls_total_lines() {
  # remove file count from ls' result
  grep -v 'total'
}

remove_ls_file_attributes() {
  # remove information about the link attributes and leave only the dereferenced link path
  sed -r 's/^.*->/->/'
}

remove_non_files() {
  # remove everything that is not an actual file - stuff like sockets and so on
  grep -v -e '-> \w'
}

main