sed -i '$a\curl -s http://whatismyip.org/' file
Trying to find a way to pull the WAN IP and insert it into the last line of a file as illustrated above (not working of course). This will be utilized via command line.
sed -i '$a\test' file
This will insert "test" after the last line in "file" as utlilized but how could I output the result of a function or command in it's place within Sed's syntax? Any suggests (awk, perl, bash script?) are welcome!
sed isn't required here. Just use this:
curl -s http://whatsmyip.org >> your.file
Note that bash supports the >> redirection operator which appends a program's output to a file
hek2mgl has shown you how to solve this specific problem. To address the more general question, you can do:
var=$(some command line)
This sets the shell variable $var to the output of the command. Then you can subsitute this into sed with:
sed -i "\$a\\$var" file
\\ escape text input so a variable can be called within Sed parameters? Example: read -e -p "login: " -i $NewUser sed -i -e 's|Username = "username"|Username = "$NewUser"|g' loginfile.foo
\\ is an escaped slash, so that the slash doesn't escape the $ after it, which allows the shell to expand the variable inside the sed parameter.