I am learning Bash scripts.
my data.txt contains:
A Orange
B Apple
I have tried
echo "enter"
read fruit
awk -F'[: ]' '$2 == "Apple"' data.txt
a=`awk -F'[: ]' '\$2 == "$fruit"' data.txt` # returns null
echo "$a"
Why isn't my awk command is not working when I am using my variable 'a' with it?
The crux of the problem is that you're trying to use a single-quoted string as if it were a double-quoted one.
What you meant to do when you used:
'\$2 == "$fruit"' # DOES NOT WORK - nothing is escaped or expanded
was:
"\$2 == \"$fruit\"" # keep literal $2, expand $fruit
Anything inside a single-quoted shell string is taken literally, so variable references aren't expanded, and nothing needs escaping - nor indeed can be escaped (the \ would become a literal part of the string too).
That said, it's better to keep the worlds of the shell and the Awk script separate, so as to prevent confusion, which means:
-v option to create Awk variables.If we put it all together:
a=$(awk -F'[: ]' -v fruit="$fruit" '$2 == fruit' data.txt)
Note that I've used modern command-substitution syntax $(...), which is preferable to legacy syntax `...`.
