How can I do something for each line of a file using bash loop?

Question

ckim@ckim-ubuntu:~/test$ cat tt
#define a b
#define c d
ckim@ckim-ubuntu:~/test$ for i in `cat tt`; do echo $i; done
#define
a
b
#define
c
d

The $i variable is taking every single word seperated by space or enter. How can I make $i represent each line from the cat command? Either using for or while is ok for me and this is bash. Thank you!

ADD : I can iterate through the line by while read line; do echo $line; done < tt but I want to do something for each line, and if I pass this output to a for loop, it's all separated to each word.

Answer 1

From comment from @glennjackman, I leared how to do it. This is what I originally wanted to do (grep a file and extract the file path in front of :).

ckim@ckim-ubuntu:~/U-BOOT/u-boot$ cat tt
dir0/Kconfig:config SUPPORT_SPL
dir1/Kconfig:select SUPPORT_SPL
dir2/Kconfig:select SUPPROT SPL
ckim@ckim-ubuntu:~/U-BOOT/u-boot$ while IFS= read -r i; do echo "${i%:*}"; done < tt
dir0/Kconfig
dir1/Kconfig
dir2/Kconfig

Answer 2

Your addition seems to work the way you want:

#!/bin/sh
while read line; do
    echo "$line"
done < tt

Output:

#define a b
#define c d