Variable lab with printing uptime of the system

Shell Scripting
#1

Hi folks. Please share a solution for the lab. Thanks

#2

Please share link to the lab so we can easily get to it.

#3

Thanks for the prompt response, Alistair! Here it is Shell Scripts for Beginners | KodeKloud

#4

The issue with this script is that the variable name has an illegal character in it, so is not interpreted as a variable

This is the error

./print-uptime.sh: line 1: up-time=: command not found

You need to make the name of the variable valid in both places it is used.

#5

Review the previous lecture Shell Scripts for Beginners | KodeKloud. You should be able to determine what the issue is from that.

#6

Thanks, Alistair! Could you please share the solution with explanation for this lab question?

#7

In the given script. the first line is written as

up-time=$(uptime)

…and the intention is to assign the output of the linux uptime command. to a variable.

If you review the lecture, you will find that up-time is not a valid name for a variable. Shell thinks that you are trying to run a command called up-time , (because - is valid in file names) and that command does not exist.

You must change all appearances of up-time to up_time to make it valid.

So the rule is

  • Anything that is a valid variable name, immediately followed by ‘=’ with no space is treated as a variable assignment
  • Anything else is treated as a command, and shell will attempt to run it (and fail).
#8

Thanks. No dash in variable is clear. I was confused with a dollar sign. Later I figured we have to use it because “uptime” itself is a command

#9
  • uptime is a real command, documented here, and many other places too.
  • up_time in the correct context is a variable, and with a $ in front is always a variable.
  • up-time the shell thinks you are trying to run a command, but that command doesn’t exist.
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