SHELL

check if file exists bash

FILE=/etc/resolv.conf
if [ -f "$FILE" ]; then
    echo "$FILE exists."
else 
    echo "$FILE does not exist."
fi

.sh script: check if file exist

#!/bin/bash
if [ -e x.txt ]
then
    echo "ok"
else
    echo "nok"
fi

Check is file exist shell

FILE=/etc/resolv.conf
if [ -f "$FILE" ]; then
    echo "$FILE exists."
fi

bash script if file exists

[ -f /etc/resolv.conf ] && echo "$FILE exists."