test -e filename
[ -e filename ]
 
test -f filename
[ -f filename ]

[ -f /etc/hosts ] && echo "Found" || echo "Not found"

Found

#!/bin/bash
file="/etc/hosts"
if [ -f "$file" ]
then
 echo "$file found."
else
 echo "$file not found."
fi

  -b FILE
    FILE exists and is block special
  -c FILE
    FILE exists and is character special
  -d FILE
    FILE exists and is a directory
  -e FILE
    FILE exists
  -f FILE
    FILE exists and is a regular file
  -g FILE
    FILE exists and is set-group-ID
  -G FILE
    FILE exists and is owned by the effective group ID
  -h FILE
    FILE exists and is a symbolic link (same as -L)
  -k FILE
    FILE exists and has its sticky bit set
  -L FILE
    FILE exists and is a symbolic link (same as -h)
  -O FILE
    FILE exists and is owned by the effective user ID
  -p FILE
    FILE exists and is a named pipe
  -r FILE
    FILE exists and read permission is granted
  -s FILE
    FILE exists and has a size greater than zero
  -S FILE
    FILE exists and is a socket
  -t FD file descriptor FD is opened on a terminal
  -u FILE
    FILE exists and its set-user-ID bit is set
  -w FILE
    FILE exists and write permission is granted
  -x FILE
    FILE exists and execute (or search) permission is granted

if [ operator FileName ]
then
  echo "FileName - Found, take some action here"
else
 echo "FileName - Not found, take some action here"
fi