[SOLVED] Unable To Concatenate 2 Linux Variables Into 1

Issue

I'm trying to concatenate two variables in linux tectia SSH into one variable, separated by "_". For some reason only one of the two variables is printed out.

I've tried to concatenate via " " e.g.:

sample1="$var1_$var2"

or

sample1="$var1 _ $var2"

and I've tried to concatenate directly e.g.:

sample1=$var1_$var2

Would appreciate any help given!

cnt_abr1=ab
cnt_abr2=cd
cnt_abr3=ef
env_abr1=a
env_abr2=b
sample1="$env_abr1_$cnt_abr1"
sample2=$env_abr2_$cnt_abr3
echo $sample1
echo $sample2

Output:

 _ ab
ef

Solution

Since underscores are effectively letters, bash has no way of knowing when your variable name ends and your literal underscore begins. The proper way to reference the variables is with ${...} in this case, which unambiguously delimits the name from the rest of the command line:

sample1="${env_abr1}_${cnt_abr1}"
sample2=${env_abr2}_${cnt_abr3}

In both cases, the second name does not require special treatment. Any other (semantically valid) non-letter character would do as well, as you pointed out in your comment:

sample1="$env_abr1"_"$cnt_abr1"
sample2="$env_abr2"_"$cnt_abr3"

Answered By - Mad Physicist