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 usingbash conditional execution:
[ -f /etc/hosts ] && echo "Found" || echo "Not found" |
Sample outputs:
Found
The same code can be converted to use withif..else..fiwhich 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)
The syntax is same (seeFile operators (attributes) comparisonsfor more info):
if [ operator FileName ] then echo "FileName - Found, take some action here" else echo "FileName - Not found, take some action here" fi |
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