How to check if a file exists using Bash Shell

Preface

You may often encounter such needs when working. In the Bash environment of a Unix-like system, how to check whether a file exists? Since there is a need, of course there is a solution. The test command in the Shell can be used to detect the type of the file or compare whether the values ​​are equal. This command can also be used to check whether the file exists.

You can use the following command to check:

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

The following command uses Shell’s conditional expression to determine /etc/ Whether the hosts file exists:

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

This combined command will output the following:

Found

The more common usage is to place the test command in the conditional expression of if..else..fi conditional judgment, and then write different branch logic in it

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

Related operators for detecting file attributes

If the file exists and has corresponding attributes, the following operators will return true:

-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

The above commands are copied from man test.

The method of using the above symbols is exactly the same:

if [ operator FileName ]
then
  echo "FileName - Found, take some action here"
else
 echo "FileName - Not found, take some action here"
fi

##Summary

The above is the entire content of this article, I hope The content of this article can be of certain help to everyone's study or work. If you have any questions, you can leave a message to communicate.

For more related articles on how to use Bash Shell to check whether a file exists, please pay attention to the PHP Chinese website!