UNIX for Dummies Questions & Answers

So I'm trying to figure out a way to do some very simple formatting on standard output. I have a command that I will run (many many times) the output will either be true or false. So all i really want is to run the command and if its true write true in green and if its false to write false in red. Ideally I don't want to be writing anything or reading anything from files. Simply run command and take the output and print it. Nothing permanent saved.

I can use awk with print to simply take standard output and format it how I want. I can't seem to get my if/else working with awk though. Is there some other way I can simply pipe standard output to a true / false logic that might be simpler than awk?

---------- Post updated at 12:11 PM ---------- Previous update was at 11:39 AM ----------

Code:

command | awk '{if($0 eq true) print "\033[1;32m" $0; else print "\033[1;31m" $0}'

This is what i'm doing now... Seems like the simplest possible way I can do it and it kinda works. It prints the output but my if doesn't seem to be working.. no matter what $0 is I get the same color output.

true is an integer, 1. "true" is a string.

So command | awk '{if($0 == "true") print "\033[1;32m" $0; else print "\033[1;31m" $0}'

Hate to beat a dead horse, but with regards terminal capabilities, it's still "better" to not hardcode terminal specifics but to query and use terminal capabilities (e.g. from terminfo database).

So, better might be:

Code:

green=`tput setaf 2`
red=`tput setaf 1`
norm=`tput sgr0`

command | awk 'BEGIN {red="'"$red"'";green="'"$green"'";norm="'"$norm"'";}{if($0 == "true") print green $0 norm; else print red $0 norm}'

and with that said, realize that the color table isn't guaranteed on a terminal... and changing it can be easy to difficult... and in some cases if you do change it, you'll want to change it back to whatever it was originally... again, you hope the terminal capabilities are there for all of that.... YMMV.

As long as all he's doing is colors it ought to be just fine.

---------- Post updated at 02:31 PM ---------- Previous update was at 02:27 PM ----------

You should use -v for setting outside variables in awk.

Code:

echo false | awk -v R="`tput setaf 1`" -v G="`tput setaf 2`" -v N="`tput sgr0`" '{if($0 == "true") print G $0 norm; else print R $0 norm}'

The -v option is not uniformly supported.. but certainly, if it's there, use it (if you don't mind sacrificing some portability).

If your system has an awk that bad, it probably has a nawk you should be using instead...

Appreciate all the answers. So far I have made so much progress on my custom prompt and i'm quite happy with the results. It's so streamline and customized that it answers about 20 different questions about the system at a glance. The last thing i'm trying to do involves the same process but I need to be able to compare sdout with a variable in side of awk. I can't seem to get it to work with a variable. The output of the command will be the IP address the hostname resolves to and the variable $actualip is the actual configured IP on the system. So the idea is that they will match when properly configured.

Code:

command | awk '{if($0==$actualip) print "\033[5;33m" $0 "\033[0;35m\" ;  else print "\033[0;32m" $0}'