Analyzing the NGINX web server log file

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1.0 Introduction

Given an nginx web server log file, we might like to know who are the visitors to our website. One can go line by line through the log file, but that is tedious. It would be nice if we can get one line per client visiting the website, giving the IP address of the visitor and how many times that client has visited.… Read more

Bash idioms

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In a nutshell

bash idioms are tiny scripts, mostly one-liners, that accomplish a lot and can be used as building blocks in bigger scripts.

1.0 Find most frequent words

Suppose we have a bunch of text files and we wish to find the most frequently used words in those files, we can do that with the command,

cat * | tr -sc '[:graph:]' '\n' | sort | uniq -c | sort -nr

First, we capture all input with cat and pipe it to the tr command.… Read more

Sed command in Linux

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1.0 sed

sed is a stream editor that accepts a list of commands and input file names. It applies the commands one by one on each line of input and writes the resulting lines on the standard output. The commands are separated by newlines.… Read more

Bash Scripting Tutorial

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1.0 Bash Script

bash can be run interactively, as a login shell or as an interactive process from a terminal emulator like the gnome-terminal. bash can be run non-interactively by running a bash script. A bash script is a list of commands written to automate some system operations work in Linux.… Read more

iptables command in Linux

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1.0 iptables

The iptables command is for defining rules for packet filtering for establishing and configuring firewalls in Linux. iptables, also, helps in configuring the Network Address Translation (NAT) for placing a local area network behind a single public IP address for accessing the Internet and for other uses.… Read more