Bash Shell : Check File Exists or Not

How do I test existence of a text file in bash running under Unix like operating systems?

You need to use the test command to check file types and compare values. The same command can be used to see if a file exist of not. The syntax is as follows:

 
test -e filename
[ -e filename ]
 
test -f filename
[ -f filename ]
 

The following command will tell if a text file called /etc/hosts exists or not using bash conditional execution :

 
[ -f /etc/hosts ] && echo "Found" || echo "Not found"
 

Sample outputs:

Found

The same code can be converted to use with if..else..fi which allows to make choice based on the success or failure of a test command:

 
#!/bin/bash
file="/etc/hosts"
if [ -f "$file" ]
then
 echo "$file found."
else
 echo "$file not found."
fi
 

File test operators

The following operators returns true if file exists:

       -b FILE
              FILE exists and is block special
       -c FILE
              FILE exists and is character special
       -d FILE
              FILE exists and is a directory
       -e FILE
              FILE exists
       -f FILE
              FILE exists and is a regular file
       -g FILE
              FILE exists and is set-group-ID
       -G FILE
              FILE exists and is owned by the effective group ID
       -h FILE
              FILE exists and is a symbolic link (same as -L)
       -k FILE
              FILE exists and has its sticky bit set
       -L FILE
              FILE exists and is a symbolic link (same as -h)
       -O FILE
              FILE exists and is owned by the effective user ID
       -p FILE
              FILE exists and is a named pipe
       -r FILE
              FILE exists and read permission is granted
       -s FILE
              FILE exists and has a size greater than zero
       -S FILE
              FILE exists and is a socket
       -t FD  file descriptor FD is opened on a terminal
       -u FILE
              FILE exists and its set-user-ID bit is set
       -w FILE
              FILE exists and write permission is granted
       -x FILE
              FILE exists and execute (or search) permission is granted

  (Fig.01: File test operators taken from bash man page)   if [ operator FileName ] then echo "FileName - Found, take some action here" else echo "FileName - Not found, take some action here" fi

With the help of BASH shell and IF command it is possible to find out if file exists or not. Generally, this is known as conditional expressions. Conditional expressions are used by the [[ compound command and the test and [ builtin commands to test file attributes and perform string and arithmetic comparisons. General syntax:

[ parameter FILE ]
OR
test 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

Examples

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

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

Find out if directory /var/logs exists or not

Type the following commands:
$ [ -d /var/logs ] && echo "Directory exists" || echo "Directory does not exists"
$ [ -d /dumper/fack ] && echo "Directory exists" || echo "Directory does not exists"
You can use conditional expressions in a shell script:

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

Save and execute the script:
$ chmod +x script.sh
$ ./script.sh /path/to/file
$ ./script.sh /etc/resolv.conf