whats wrong with this bash script:
acme2=$(dig txt @$1 _acme-challenge.$1.de) acme3=$(echo $acme2 | grep "^_acme") acme2 has the whole output, but acme3 is always empty
I searched several solutions, and tried other possibilities, but nothing works...
acme3=echo $acme2|grep acme acme3=$($acme2|grep "^_acme") acme3=$(grep "acme" $acme2) acme3=$(echo "$acme2" | grep "^_acme") We really can't help since we have no idea what $acme2 contains, but I can tell you that your grep command is looking for lines that start with _acme. Since the output of dig is multiple lines and you are echoing the variable unquoted, that will put everything on a single line, so unless the very first string in the output is _acme, your grep will match nothing. To illustrate:
$ seq 3 1 2 3 $ acme=$(seq 3) $ echo $acme 1 2 3 $ echo "$acme" 1 2 3 $ echo $acme | grep '^2' $ $ echo "$acme" | grep '^2' 2 So, assuming you have at least one line in your dig output that begins with _acme, correctly quoting your variable (which you should ALWAYS do, by the way) should work:
acme3=$(echo "$acme2" | grep "^_acme") Or, better, especially for arbitrary data like this:
acme3=$(printf '%s\n' "$acme2" | grep "^_acme") 
grep "^_acme" <<<$acme2 -- herestring doesn't wordsplit or glob and adds newline (except in rc-family, per Stephane C)CommentedFeb 13 at 2:38dig txt @$1 _acme-challenge.$1.de, which means we cannot know what you have in the acme2 variable. When you ask questions asking for help parsing data, it is important to show the data you want to parse. Your dig might not be the same as my dig, and even if they are, the output depends on what you are looking at. So please show us the actual content of your variables.Both lines could be coalesced by telling dig you're only interested in its direct output:
#!/bin/sh acme3=$(dig +short txt @"$1" "_acme-challenge.$1.de") This also sidesteps the issue with echo $acme2, which should almost certainly have been echo "$acme2" or even printf '%s\n' "$acme2". (Omitting the double quotes causes the contents of the variable $acme2 to be split on characters of $IFS (space, tab and newline by default) and subject to glob expansion which when passed to echo likely results in the full output ending up as a single line, possibly modified beyond recognition.)
$1. You used that in your example so I assumed you'd have known how to use it in in my solution. (Min d you, I don't think your dig command would ever have returned anything. But without knowing what you're trying to do, and having an example of $1 I can't correct your code.)CommentedFeb 21 at 14:32
$1? You should post the debug withset -xprintf '%s\n' "$acme2". We really can't help you parse data you don't show us. And clarify exactly what you want to do here. What is the expected output? Why are you expecting a line beginning with_acme?typeset -p acme2and b) the expected contents ofacme3echo $acme2as-is, you'd have seen it folds all the lines into one, perhaps explaining why thegrepdoesn't stick.