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Here are the different ways to store the output of a command in shell script. You can also use these commands on terminal to store command outputs in shell variables. variable_name=$(command) variable_name=$(command [option ...] arg1 arg2 ...) OR variable_name=`command` variable_name=`command [option ...]
$1 is the first argument (filename1) $2 is the second argument (dir1)
The echo command is used to display a line of text that is passed in as an argument. This is a bash command that is mostly used in shell scripts to output status to the screen or to a file.
In shell, you don't put a $ in front of a variable you're assigning. You only use $IP when you're referring to the variable.
#!/bin/bash
IP=$(curl automation.whatismyip.com/n09230945.asp)
echo "$IP"
sed "s/IP/$IP/" nsupdate.txt | nsupdate
Same with something more complex...getting the ec2 instance region from within the instance.
INSTANCE_REGION=$(curl -s 'http://169.254.169.254/latest/dynamic/instance-identity/document' | python -c "import sys, json; print json.load(sys.stdin)['region']")
echo $INSTANCE_REGION
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