Method: We can write our own script using the ping command to query list of IP addresses and check whether they are alive or not as follows:

#!/bin/bash

#Filename: ping.sh

# Change base address 192.168.0 according to your network.

for ip in 192.168.0.{1..255} ;

do
       #Amount of packets transmitted "-c 2"
       #/dev/null is a virtual file. This will discard anything written to it.

ping $ip -c 2 &> /dev/null ;

if [ $? -eq 0 ];

then

echo $ip is alive

fi

done

cat < /dev/tcp/IP/PORT

cat < /dev/tcp/192.90.70.200/3306

OR

curl -v telnet://ip:port'

curl -v telnet://192.90.70.200:3306

curl -v telnet://192.90.70.2001:3306

#!/bin/bash

echo "----------------------------"

echo "Sourcing Functions:"

echo "----------------------------"

echo " - nodes_up: Checks what hosts are up or down using nmap"

echo " - slbs_status: Check if NGINX Process and Status in AZ1 & AZ2"

echo " - slbs: Check if NGINX nodes are up / down using nmap in AZ1 & AZ2"

echo " - service_db_netwk: Checks connectivity between the Service in AZ1 and MySQL in AZ2 and vice-versa"

echo " - tail_service_log: Tail 100 lines of the service.lo...

Print column 1 & 2

ps | awk '{print $1,$2}'

To separate the columns titles you can use "\t" between the numbers:

ps | awk '{print $1"\t"$2}'

By default the field separator for awk is a space, if it's not the case tell awk which one it is by using F for field separator. In the example of /etc/passwd file the separator is semi-colon

awk -F ":" '{print $1}' /etc/passwd

You can also grep:

awk -F ":" '{print $1}' /etc/passwd | grep myservice

To search for every last field in the line, but r...

sed > Stream editor allow filter and transform texts, find pattern and replace with whatever is that you want to replace with, it's like search and replace.

You can use other separators instead of slashes (/). Example pipe | or hash #

1 - sed substitution -- s for substitution. replaces only the first occurrence in each line of the file and save to a new file

sed 's/word/newword/' < oldfile > newfile

2 - replaces every occurrence of 'word'. g for global

sed 's/word/newword/g' < oldfi...