Bash
I have a list of IPs in MAXCDN_ARRAY to be used as whitelist. I want to check if a specific IP address is in range in this array. How can I structure the code so that it can compare all IPs in the array and say the specific IP in in range of this list or not?
GrepCIDR
You can use grepcidr to check if an IP address is in a list of CIDR networks.
The following is a list of variables that awk sets automatically on certain occasions in order to provide information to your program. The variables that are specific to gawk are marked with a pound sign (#). These variables are gawk extensions. In other awk implementations or if gawk is in compatibility mode (see section Command-Line Options ), they are not special.
| VARIABLE NAME | DESCRIPTION |
|---|---|
| FS | input field separator variable |
| OFS | Output Field Separator |
| RS | Input Record Separator variable |
| ORS | Output Record Separator Variable |
| NR | Number of Records |
| NF | Number of Fields in a record |
| FILENAME | Name of the current input file |
| FNR | Number of Records relative to the current input file |
| RLENGTH | length of the substring matched by the match() function |
| RSTART | first position in the string matched by match() function |
FS - input field separator variable
It represents the (input) field separator and its default value is space. You can also change this by using -F command line option.
In this awk tutorial, let us review awk conditional if statements with practical examples.
Normally conditional statement checks the condition, before performing any action. If the condition is true action(s) are performed. Similarly action can be performed if the condition is false.
Conditional statement starts with the keyword called "if". Awk supports three different kind of if statement.
awk If Statement
Single Action: Simple If statement is used to check the conditions, if the condition returns true, it performs its corresponding action(s).
