How to assign multiple string values into a variable in shell scripts? - shell

Question

I'm trying to loop a text file changing the number and the hole string is store into a shell variable, to print it latter
I've tried echo the string an the integer (number from the loop) using ">>"
#!/bin/bash
a=0
while [ "$a" -lt 4 ]
do
echo '<div name="block-'${a}'">' >> $sub_main
((a++))
done
echo "done"
echo $sub_main
The output from the script should be:
<div name="block-0">
<div name="block-1">
<div name="block-2">
<div name="block-3">

Answer 1

>> appends the out putto a file. If you want to append to a variable you can use an assignment with the variable to append to at the beginning of the right value.
a=0;
sub_main="";
while [ "${a}" -lt 4 ]; do
sub_main="${sub_main}\n<div name=\"block-${a}\">";
((a++));
done;
echo "done";
echo "${sub_main}";
Or, if the appending to the file was intended, you can simply use cat instead of echo, to output the file's contents.
I.e. replace
echo $sub_main
with:
cat "${sub_main}";

Answer 2

Use command substitution to capture the output into a variable:
#!/bin/bash
sub_main=$(
for (( a = 0; a < 4; a++ )); do
printf '<div name="block-%d">\n' "$a"
done
)
# ... do other stuff ...
echo "$sub_main"
Or you might want to use a function to defer execution until later:
#!/bin/bash
sub_main() {
for (( a = 0; a < 4; a++ )); do
printf '<div name="block-%d">\n' "$a"
done
}
# ... do other stuff ...
sub_main