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?
You can use grepcidr to check if an IP address is in a list of CIDR networks.
This is not my article, it is copy from this site . It cover install icinga2 , icinga2 director and pnp4nagios on Ubuntu 20.04, but is very useful as manual for debian buster and Bullseye.
This guide shows how to install Icinga2 monitoring software on Ubuntu 20.04 – this includes backend, frontend, director and pnp4nagios (adding graphs to icinga). Especially PNP was hard to get working – but if you follow the guide everything is nicely lined up at the end.
The cut command is a command-line utility for cutting sections from each line of a file. It writes the result to the standard output. It’s worth noting that it does not modify the file, but only works on a copy of the content. Although typically the input to a cut command is a file, we can pipe the output of other commands and use it as input.
It can be used to cut parts of a line by byte position, character and field. Basically the cut command slices a line and extracts the text. It is necessary to specify option with command otherwise it gives error. If more than one file name is provided then data from each file is not precedes by its file name.
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 |
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.
Single Action: Simple If statement is used to check the conditions, if the condition returns true, it performs its corresponding action(s).
YUM (Yellowdog Updater Modified) is an open source command-line as well as graphical based package management tool for RPM (RedHat Package Manager) based Linux systems. It allows users and system administrator to easily install, update, remove or search software packages on a systems. It was developed and released by Seth Vidal under GPL (General Public License) as an open source, means anyone can allowed to download and access the code to fix bugs and develop customized packages. YUM uses numerous third party repositories to install packages automatically by resolving their dependencies issues.
