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I have a text file containing this:

Hello \"${USER}\"!
Today you drank ${COFFEE_COUNT} coffees.
See you tomorrow!

Now I have a bash script running that has these strings assigned (and exported). But when that script echoes this file it doesn't replace the strings.

... code ...

export COFFEE_COUNT="$(some code)"   #${USER} is set by default

... code ...

t=$(wc -l < ${scriptdir}/COFFEE);
for ((l=1;l<t;l++));
do
    echo $(sed -n "${l}{p;q;}" < ${scriptdir}/COFFEE);
done;

... code ...

nor does cat work

cat "${scriptdir}/COFFEE";

Is there a way to make this work?

required output:

Hello "username"!
Today you drank 3 coffees.
See you tomorrow!
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1
  • Where does input for the required output come from? Where is COFFEE_COUNT set? Commented Jan 6, 2018 at 22:45

2 Answers 2

Reset to default
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bash only expands variables in its code but not those within variables (or other expansions') data. Si instead of

echo $(sed -n "${l}{p;q;}" < ${scriptdir}/COFFEE)

you need

eval echo \""$(sed -n "${l}{p;q;}" < ${scriptdir}/COFFEE)"\"
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2
  • The use of eval is regarded as insecure, bad habit. Commented Jan 7, 2018 at 0:06
  • @isaac It may be a bad habit if it is not necessary. Commented Jan 7, 2018 at 0:16
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Why use an additional file when a here-doc could do the job:

#!/bin/bash

export COFFEE_COUNT=$1   #${USER} is set by default
export USER=username

cat <<_EOT_
Hello "${USER}"!
Today you drank ${COFFEE_COUNT} coffees.
See you tomorrow!
_EOT_

On execution:

$ ./script 13
Hello "username"!
Today you drank 13 coffees.
See you tomorrow!
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1
  • I could but the text can be different every time. I have multiple files which are used in the same command. This COFFEE file is just an example. It also makes it easier to be edited later on instead of opening the code and making a mistake. I also need to be able to only echo specific lines and not the whole file. Good suggestion for fixed output though. Thank you. Commented Jan 8, 2018 at 17:18

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