if condition one liners

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To check if a file exists or not (of any type)

if [ -a $file_name ]

then

      echo "File $file_name exists";

else

      echo "File $file_name does not exists";

fi

OR

if [ -e $file_name ]

then

      echo "File $file_name exists";

else

      echo "File $file_name does not exists";

fi

To check if a file of block special type exists or not

if [ -b $file_name ]

then

      echo "Block File $file_name exists";

else

      echo "Block File $file_name does not exists";

fi

To check if a file of character special type exists or not

if [ -c $file_name ]

then

      echo "Character File $file_name exists";

else

      echo "Character File $file_name does not exists";

fi

To check if a file of type directory exists or not

if [ -d $folder_name ]

then

      echo "Directory $folder_name exists";

else

      echo "Directory $folder_name does not exists";

fi

To check if a file of type symbolic link exists or not

if [ -h $file_name ]

then

      echo "File $file_name exists which is a symbolic link";

else

      echo "File $file_name does not exists or not a symbolic link";

fi

OR

if [ -L $file_name ]

then

      echo "File $file_name exists which is a symbolic link";

else

      echo "File $file_name does not exists or not a symbolic link";

fi

To check if a file of regular type exists or not

if [ -f $file_name ]

then

      echo "Regular file $file_name exists";

else

      echo "Regular file $file_name does not exists";

fi

To check if a file exists or not and its SGID bit is set or not

if [ -g $file_name ]

then

      echo "File $file_name with SGID bit on exists";

else 

      echo "File $file_name does not exists or SGID bit is off";

fi

To check if a file exists or not and its STICKY bit is set or not

if [ -k $file_name ]

then

      echo "File $file_name with SGID bit on exists";

else

      echo "File $file_name does not exists or SGID bit is off";

fi

To check if a file of PIPE special type exists or not

if [ -p $file_name ]

then

      echo "Named PIPE File $file_name exists";

else

      echo "Named PIPE File $file_name does not exists";

fi

To check if a file exists and readable or not to current user 

if [ -r $file_name ]

then

      echo "File $file_name exists and is readable";

else

      echo "File $file_name does not exists or its not readable ";

fi

To check if a file exists and is of nonzero size

if [ -s $file_name ]

then

      echo "File $file_name exists and is nonzero size";

else

      echo "File $file_name does not exists or is of zero size";

fi

To check if a file exists or not and its SUID bit is set or not

if [ -u $file_name ]

then

      echo "File $file_name exists and is readable";

else

      echo "File $file_name does not exists or is not readable ";

fi

To check if a file exists and writable or not to current user 

if [ -w $file_name ]

then

      echo "File $file_name exists and is writable";

else

      echo "File $file_name does not exists or is not writable ";

fi

To check if a file exists and executable or not to current user 

if [ -x $file_name ]

then

      echo "File $file_name exists and is executable";

else

      echo "File $file_name does not exists and is not executable ";

fi

To check if a file of socket special type exists or not

if [ -S $file_name ]

then

      echo "Socket File $file_name exists";

else

      echo "Socket File $file_name does not exists";

fi

To check if a file newer than other or not

# touch file_name2 file_name1

# ls -lrt file_name*                                       

-rw-r--r--. 1 root root 0 Nov 12 22:54 file_name2

-rw-r--r--. 1 root root 0 Nov 12 22:54 file_name1

# if [ $file_name1 -nt $file_name2 ];

then

echo "File $file_name1 is Newer than $file_name2 ";

else

echo "File $file_name1 is Older than $file_name2 ";

fi

# touch file_name2

# ls -lrt file_name*

-rw-r--r--. 1 root root 0 Nov 12 22:54 file_name1

-rw-r--r--. 1 root root 0 Nov 12 22:58 file_name2

# if [ $file_name1 -nt $file_name2 ];

then

echo "File $file_name1 is Newer than $file_name2 ";

else

echo "File $file_name1 is Older than $file_name2 ";

fi

# touch file_name1

# ls -lrt file_name*

-rw-r--r--. 1 root root 0 Nov 12 22:54 file_name1

-r////w-r--r--. 1 root root 0 Nov 12 22:57 file_name2

# if [ $file_name1 -nt $file_name2 ]

then

echo "File $file_name1 is Newer than $file_name2 ";

else

echo "File $file_name1 is Older than $file_name2 ";

fi

To check if a file older than other or not

# touch file_name2 file_name1

# ls -lrt file_name*                                       

-rw-r--r--. 1 root root 0 Nov 12 22:54 file_name2

-rw-r--r--. 1 root root 0 Nov 12 22:54 file_name1

# if [ $file_name1 -ot $file_name2 ];

then

echo "File $file_name1 is Older than $file_name2 ";

else

echo "File $file_name1 is Newer than $file_name2 ";

fi

# touch file_name2

# ls -lrt file_name*

-rw-r--r--. 1 root root 0 Nov 12 22:54 file_name1

-rw-r--r--. 1 root root 0 Nov 12 22:58 file_name2

# if [ $file_name1 -ot $file_name2 ];

then

echo "File $file_name1 is Older than $file_name2 ";

else

echo "File $file_name1 is Newer than $file_name2 ";

fi

# touch file_name1

# ls -lrt file_name*

-rw-r--r--. 1 root root 0 Nov 12 22:54 file_name1

-rw-r--r--. 1 root root 0 Nov 12 22:57 file_name2

# if [ $file_name1 -ot $file_name2 ];

then

echo "File $file_name1 is Older than $file_name2 ";

else

echo "File $file_name1 is Newer than $file_name2 ";

fi

To check whether string variable is zero or not

# if [ -z $variaible ];

then

echo "String is zero ";

else

echo " String is nonzero ";

fi

To check whether length of string variable is nonzero

# if [ -n $variaible ];

then

echo "String length is nonzero ";

else

echo " String length is zero ";

fi

OR

# if [ $variaible ];

then

echo "String length is zero ";

else

echo " String length is nonzero ";

fi

To check two string variables are matching or not

# if [ $variaible1 == $variable2 ];

then

echo "Both Variables are matching ";

else

echo "Both Variable are not matching ";

fi

OR

# if [ $variaible1 != $variable2 ];

then

echo "Both Variables are not matching ";

else

echo "Both Variable are matching ";

fi

To check two integer variables are equal or not

# if [ $value1 -eq $value2 ];

then

echo "Both Values are equal";

else

echo "Both Values are not equal ";

fi

OR

# if [ $value1 -ne $value2 ];

then

echo "Both Values are not equal";

else

echo "Both Values are equal ";

fi

To check which integer variable is smaller

# if [ $value1 -gt $value2 ];

then

echo " $value1 is greater than $value2";

else

echo " $value1 is less than or equal to $value2";

fi

OR

# if [ $value1 -lt $value2 ];

then

echo " $value1 is less than $value2";

else

echo " $value1 is greater than or equal to $value2";

fi

OR

# if [ $value1 -ge $value2 ];

then

echo " $value1 is greater than or equal to $value2";

else

echo " $value1 is less than $value2";

fi  

OR

# if [ $value1 -le $value2 ];

then

echo " $value1 is less than or equal to $value2";

else

echo " $value1 is greater than $value2";

fi 

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