How to check if a file exists in Linux bash shell?

To check if a file exists in a bash shell script, use the following:

FILE="/some/path/file"

if [ -f "$FILE" ]; then
  # perform some action if $FILE exists.
fi

FILE="/some/path/file"

if [ -f "$FILE" ]; then

# perform some action if $FILE exists.

To check if a file does not exists in a bash shell script, use the following:

if [ ! -f "$FILE" ]; then
  # perform some action if $FILE does not exists.
fi

if [ ! -f "$FILE" ]; then

# perform some action if $FILE does not exists.