I'm trying to use the hostname of a linux device into a string for that here's what I'm trying:
app.sh
flowname="flow_${hostname}.txt"
echo "$flowname"
running the script delivers the following output : flow_.txt
any idea what I'm missing here ?
thanks in advance !
The ${VARIABLE} syntax is used to substitute the value of the given variable.
You want to execute the hostname command.
By using the above variable substitution you try to output a variable called 'hostname' which does not exist.
You have to use the $(COMMAND) syntax. This will execute the given command and print its result.
There's no built-in variable named $hostname. Try the variable $HOST or the command substitution $(hostname) instead.
flowname="flow_$HOST.txt"
flowname="flow_$(hostname).txt"
Try "uname -n", the "uname" command gives interesting information on your host.
I tried your script under ubuntu on WSL (windows subsytem for linux) and found the comment of John Kugelman useful.
To make the script functioning in this environment, i first print out the available system environment variables.
printenv | less
then I chosen to replace ${hostname} with ${NAME}.
You need variables that are populated. Use the command env to list environment variables,
env
So, just populate hostname,
hostname=$(uname -n)
echo ${hostname}
flowname="flow_${hostname}.txt"
echo "$flowname"
