Expression Example

Here are some common expression which can use with if condition

Check Directory
-d file >> True if file is a directory

#!/bin/bash
if [ -d /home ]; then
echo "/home is directory"
else
echo "/home is not directory"
fi

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Check the file is exists
-e file >>True if file exists.

#!/bin/bash 

if [ -e /home/admin/.bash_profile ]; 

then 

echo ".bash_profile exists" 

else 

echo ".bash_profile not exists" 

fi

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Check the file is regular file
-f file >>True if file exists and is a regular file

#!/bin/bash 

if [ -f /etc/passwd ]; then  

echo "/etc/passwd file is regular file" 

else 

echo " /etc/passwd file is not regular file "

fi

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#!/bin/bash 

if [ -f /dev/fd0 ] then 

echo "regular file" 

else 

echo "not regular file" 

fi

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Check the file has symbolic link
-L file >>  True if file is a symbolic link

#!/bin/bash 

if [ -L /dev/cdrom ] then 

echo "symbolink link file" 

else 

echo "not symbolink link file" 

fi

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Check read, write execute permission
-r file >> True file is readable
-w file >> True file is writeable
-x file >> True file is executable

#!/bin/bash 

if [ -r /etc/passwd ] then 

echo "file is readable" 

else 

echo "file is not readable" 

fi

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Check new or old file
file1 -nt file2 >> True  file1 newer than file2
file1 -ot file2 >> True  file1 older than file2

#!/bin/bash 

if [ /home/admin/test1 -nt /home/admin/test2] then 

echo "file test1 is new" 

else 

echo "file test2 is new" 

fi

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