Check if arguments[files] exist or not in bash - bash

Question

This is part of my script:
#!/bin/bash
USAGE(){
echo "Usage: ./`basename $0` <File1> <File2>"
}
if [ "$#" -ne "2" ]; then
USAGE
exit 1
fi
if [ ! -f "$1" ]; then
echo "The file \"$1\" does not exist!"
exit 1
fi
if [ ! -f "$2" ]; then
echo "The file \"$2\" does not exist!"
exit 1
fi
I want to check if file1 does not exist prints:
The file "file1" does not exist!
if file2 does not exist prints:
The file "file2" does not exist!
If both does not exist prints:
The files "file1" and "file2" don't exist!
How can I do that?
I want to know what the most logical (STANDARD) method is.

Answer 1

Of course you can do that... . There are many ways to obtain this. The most simple maybe:
if [ ! -f "$1" ] && [ ! -f "$2" ]; then
echo "The files \"$1\" and \"$2\" do not exist!"
exit 1
else
if [ ! -f "$1" ]; then
echo "The file \"$1\" does not exist!"
exit 1
fi
if [ ! -f "$2" ]; then
echo "The file \"$2\" does not exist!"
exit 1
fi
fi
If you don't want to do the checks two time, you can work with variables; something like this:
if [ ! -f "$1" ]; then
NOT1=1
fi
if [ ! -f "$1" ]; then
NOT2=1
fi
if [ -n "$NOT1" ] && [ -n "$NOT2" ]
....

Answer 2

You could do it like this so you only have to test each file once:
status=""
for file; do
[ -f "$file" ]
status+=$?
done
case $status in
11)
echo "The files \"$1\" and \"$2\" do not exist!"
exit 1
;;
10)
echo "The file \"$1\" does not exist!"
exit 1
;;
01)
echo "The file \"$2\" does not exist!"
exit 1
;;
esac

Answer 3

The logical is
if [ ! -f "$1" ]; then
if [ ! -f "$2" ]; then
echo "The files \"$file1\" and \"$file2\" don't exist!"
exit 1
else
echo "The file \"$1\" does not exist!"
exit 1
fi
fi
if [ ! -f "$2" ]; then
echo "The file \"$2\" does not exist!"
exit 1
fi
The readable is
if [ ! -f "$1" -a ! -f "$2" ]; then
echo "The files \"$file1\" and \"$file2\" don't exist!"
exit 1
fi
if [ ! -f "$1" ]; then
echo "The file \"$1\" does not exist!"
exit 1
fi
if [ ! -f "$2" ]; then
echo "The file \"$2\" does not exist!"
exit 1
fi
The readable is preferred.
Also not testing for existence twice as Chris Maes said could be logical too.

Answer 4

Simplified for Bash:
#!/bin/bash
if [[ $# -ne 2 ]]; then
echo "Usage: ${0##*/} <File1> <File2>"
elif [[ ! -f $1 && ! -f $2 ]]; then
echo "The files \"$1\" and \"$2\" don't exist!"
elif [[ ! -f $1 ]]; then
echo "The file \"$1\" does not exist!"
elif [[ ! -f $2 ]]; then
echo "The file \"$2\" does not exist!"
fi

Answer 5

You can use this additional condition:
if [ ! -f "$1" ] && [ ! -f "$2" ]; then
echo "Both files does not exist!"
exit 1
fi
I'm not sure you need that though. The two conditions you have, for first and second file, will be informative enough.
Alternatively, you can use just one condition by using logical OR ||. I'd suspect users wouldn't have an issue with understanding their misues of the script:
if [ ! -f "$1" ] || [ ! -f "$2" ]; then
USAGE
exit 1
fi