timestamp in linux shell commandline / file operations

touch /root/client-01-$(date +%s)


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


[ ! -f /etc/hosts ] && echo "File does not exist" || echo "File exits"


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


#!/bin/bash
file="/.config/backup.cfg"
if [ ! -f "$file" ]
then
    echo "$0: File '${file}' not found."
fi


File test operators
The following operators returns true if file exists:

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