Just like C, awk can manipulate bits.html
AND and node
OR oride
XOR xorspa
Complement complcode
Left Shift lshifthtm
Right Shift rlshiftblog
Awk Example using Bit Functionsip
$ cat bits.awk BEGIN { number1=15 number2=25 print "AND: " and(number1,number2); print "OR: " or(number1,number2) print "XOR: " xor(number1,number2) print "LSHIFT: " lshift(number1,2) print "RSHIFT: " rshift(number1,2) }
$ awk -f bits.awk AND: 9 OR: 31 XOR: 22 LSHIFT: 60 RSHIFT: 3
Awk allows you to define user defined functions. This is extremely helpful when you are writing a lot of awk code and end-up repeating certain pieces of code every time. Those pieces could be fit into a user defined function.ci
Syntax:rem
function fn-name(parameters) { function-body }
The following example creates a simple user defined function called discount that gives a discount in the prices for the specified percentage. For example, discount(10) gives 10% discount on the price.
For any items where the quantity is <= 10, it gives 10% discount,otherwise it gives 50% discount.
$ cat function.awk BEGIN { FS="," OFS="," } { if ($5 <= 10) print $1,$2,$3,discount(10),$5 else print $1,$2,$3,discount(50),$5 } function discount(percentage) { return $4 - ($4*percentage/100) }
$ awk -f function.awk items.txt 101,HD Camcorder,Video,189,10 102,Refrigerator,Appliance,765,2 103,MP3 Player,Audio,135,15 104,Tennis Racket,Sports,95,20 105,Laser Printer,Office,427.5,5
三、Language Independent Output (Internationalization)
Awk can communication to an external process using "|&", which is two way communication.
The following simple sed example substitutes the word "Awk" with "Sed and Awk".
$ echo "Awk is great" | sed 's/Awk/Sed and Awk/' Sed and Awk is great
To understand how the two way communication from Awk works, the following awk script simulates the above simple example using "|&"
$ cat two-way.awk BEGIN { command = "sed 's/Awk/Sed and Awk/'" print "Awk is Great!" |& command close(command,"to"); command |& getline tmp print tmp; close(command); } $ awk -f two-way.awk Sed and Awk is Great!
In the above example:
• command = "sed 's/Awk/Sed and Awk/'" -- This is the command to which we are going to establish the two way communication from awk. This is a simple sed substitute command, that will replace "Awk" with "Sed and Awk".
• print "Awk is Great!" |& command -- The input to the command. i.e. The input to the sed substitute command is "Awk is Great!". The "|&" indicates that it is a two way communication. The input to the command on the right side to the "|&" comes from the left side.
• close(command,"to") - Once the process is executed, you should close the "to" process.
• command |& getline tmp - Now that the process is completed, it is time to get the output of the process using the getline. The output of the previously executed command will now be stored in the variable "tmp".
• print tmp - This prints the output.
• close(command) - Finally, close the command.
Two way communication can come-in handy when you rely heavily on output from external programs.
see: http://www.gnu.org/software/gawk/manual/html_node/Two_002dway-I_002fO.html