Linux / UNIX: Find Out If File Exists With Conditional Expressions in a Bash Shell

With the help of BASH shell and IF command, it is possible to find out if a file exists or not on the filesystem. A conditional expression (also know as “evaluating expressions”) can be used by [[ compound command and the test ([) builtin commands to test file attributes and perform string and arithmetic comparisons.


You can easily find out if a regular file does or does not exist in Bash shell under macOS, Linux, FreeBSD, and Unix-like operating system. You can use [ expression ], [[ expression ]], test expression, or if [ expression ]; then .... fi in bash shell along with a !operator. Let us see various ways to find out if a file exists or not in bash shell.

Syntax to find out if file exists with conditional expressions in a Bash Shell

The general syntax is as follows:
[ parameter FILE ]
OR
test parameter FILE
OR
[[ parameter FILE ]]
Where parameter can be any one of the following:

• -e: Returns true value if file exists.
• -f: Return true value if file exists and regular file.
• -r: Return true value if file exists and is readable.
• -w: Return true value if file exists and is writable.
• -x: Return true value if file exists and is executable.
• -d: Return true value if exists and is a directory.

Please note that the [[ works only in Bash, Zsh and the Korn shell, and is more powerful; [ and test are available in POSIX shells. Let us see some examples.

Find out if file /etc/passwd file exist or not

Type the following commands:
$ [ -f /etc/passwd ] && echo "File exist" || echo "File does not exist"
$ [ -f /tmp/fileonetwo ] && echo "File exist" || echo "File does not exist"

How can I tell if a regular file named /etc/foo does not exist in Bash?

You can use ! operator as follows:
[ ! -f /etc/foo ] && echo "File does not exist"Exists
OR

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

[[ example

Enter the following commands at the shell prompt:
$ [[ -f /etc/passwd ]] && echo "File exist" || echo "File does not exist"
$ [[ -f /tmp/fileonetwo ]] && echo "File exist" || echo "File does not exist"

Find out if directory /var/logs exist or not

Type the following commands:
$ [ -d /var/logs ] && echo "Directory exist" || echo "Directory does not exist"
$ [ -d /dumper/fack ] && echo "Directory exist" || echo "Directory does not exist"

[[ example

$ [[ -d /var/logs ]] && echo "Directory exist" || echo "Directory does not exist"
$ [[ -d /dumper/fake ]] && echo "Directory exist" || echo "Directory does not exist"

Are two files are the same?

Use the -ef primitive with the [[ new test command:

## first compare /etc/resolv.conf with /etc/resolv.conf ##
[[ /etc/resolv.conf -ef /etc/resolv.conf ]] && echo "Same files" || echo "Noop"
 
## now compare /etc/resolv.conf with /etc/passwd ##
[[ /etc/resolv.conf -ef /etc/passwd ]] && echo "Same files" || echo "Noop"

How to check if a file exists in a shell script

You can use conditional expressions in a shell script:

#!/bin/bash
FILE="$1"
 
if [ -f "$FILE" ];
then
   echo "File $FILE exist."
else
   echo "File $FILE does not exist" >&2
fi

Save and execute the script:
$ chmod +x script.sh
$ ./script.sh /path/to/file
$ ./script.sh /etc/resolv.conf
To check if a file exists in a shell script regardless of type, use the -e option:

#!/bin/bash
FILE="$1"
 
[ "$FILE" == "" ] && { echo "Usage: $0 filename"; exit 1; }
if [ -e "$FILE" ];
then
   echo "File $FILE exist."
else
   echo "File $FILE does not exist" >&2
fi

You can use this technique to verify that backup directory or backup source directory exits or not in shell scripts. See example script for more information.

A complete list for file testing in bash shell

From the test command man page:

Conclusion

You just learned how to find out if file exists with conditional expressions in a Bash shell. For more information type the following command at shell prompt or see test command in our wiki or see bash man page here:
test(1)