How to echo lines of file using bash script and for loop

Question

I have a simple file called dbs.txt I want to echo the lines of that file to the screen using a for loop in bash.

The file looks like this:

db1
db2
db3
db4

The bash file is called test.sh it looks like this

for i in 'cat dbs.txt'; do
echo $i
done
wait

When I run the file by typing:

bash test.sh

I get the terminal output:

cat dbs.txt

instead of the hoped for

db1
db2
db3
db4

The following bash file works great:

cat dbs.txt | while read line
do
echo "$line"
done

Why doesn't the first script work?

Answer 1

You need command substitution shell feature. This require the POSIX expression $().

Please, don't use backticks as others said.

The backquote (`) is used in the old-style command substitution, e.g.

foo=`command`

The

foo=$(command)

syntax is recommended instead. Backslash handling inside $() is less surprising, and $() is easier to nest. See

• http://pubs.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html -> 2.6.3 Command Substitution
• http://mywiki.wooledge.org/BashFAQ/082

Despite of what Linus G Thiel said, $() works in sh, ash, zsh, dash, bash...