How do I tell if a regular file does not exist in Bash?

The test command ([ here) has a "not" logical operator which is the exclamation point (similar to many other languages). Try this:

if [ ! -f /tmp/foo.txt ]; then     echo "File not found!" fi 

Bash File Testing

-b filename - Block special file
-c filename - Special character file
-d directoryname - Check for directory Existence
-e filename - Check for file existence, regardless of type (node, directory, socket, etc.)
-f filename - Check for regular file existence not a directory
-G filename - Check if file exists and is owned by effective group ID
-G filename set-group-id - True if file exists and is set-group-id
-k filename - Sticky bit
-L filename - Symbolic link
-O filename - True if file exists and is owned by the effective user id
-r filename - Check if file is a readable
-S filename - Check if file is socket
-s filename - Check if file is nonzero size
-u filename - Check if file set-user-id bit is set
-w filename - Check if file is writable
-x filename - Check if file is executable

How to use:

#!/bin/bash file=./file if [ -e "$file" ]; then     echo "File exists" else      echo "File does not exist" fi  

A test expression can be negated by using the ! operator

#!/bin/bash file=./file if [ ! -e "$file" ]; then     echo "File does not exist" else      echo "File exists" fi  

You can negate an expression with "!":

#!/bin/bash FILE=$1  if [ ! -f "$FILE" ] then     echo "File $FILE does not exist" fi 

The relevant man page is man test or, equivalently, man [ -- or help test or help [ for the built-in bash command.

[[ -f $FILE ]] || printf '%s does not exist!\n' "$FILE" 

Also, it's possible that the file is a broken symbolic link, or a non-regular file, like e.g. a socket, device or fifo. For example, to add a check for broken symlinks:

if [[ ! -f $FILE ]]; then     if [[ -L $FILE ]]; then         printf '%s is a broken symlink!\n' "$FILE"     else         printf '%s does not exist!\n' "$FILE"     fi fi 

It's worth mentioning that if you need to execute a single command you can abbreviate

if [ ! -f "$file" ]; then     echo "$file" fi 

to

test -f "$file" || echo "$file" 

or

[ -f "$file" ] || echo "$file"