UNIX for Beginners Questions & Answers

#!/bin/bash

printf "abc def{\x0D\x0Acdefg\x0D\x0Athis is a string\x0D\x0Afghh_hjhad_text{\x09text after brace with tab\x0D\x0A\x0D\x0A{\x0D\x0A{ text  at    end     only, (with spaces)!\x0D\x0Aabcd_123\x0D\x0Aend of file without brace\x0D\x0A" > /tmp/text
hexdump -C /tmp/text
echo "cat /tmp/text:"
echo ""

cat /tmp/text
echo "TEST FILE CREATION END, FILTER START!"
echo ""

# Working part...
while read -r line
do
    for (( n=0; n<=${#line}; n++ ))
    do
        if [ "${line:$n:1}" = "{" ]
        then
            echo "$line"
        fi
    done
done < /tmp/text > /tmp/lines
# End of working part!

echo "FILTER DONE!"
echo ""

hexdump -C /tmp/lines
echo ""
cat /tmp/lines

Last login: Sat Mar 16 23:21:49 on ttys000
AMIGA:amiga~> cd Desktop/Code/Shell
AMIGA:amiga~/Desktop/Code/Shell> ./left_brace.sh
00000000  61 62 63 20 64 65 66 7b  0d 0a 63 64 65 66 67 0d  |abc def{..cdefg.|
00000010  0a 74 68 69 73 20 69 73  20 61 20 73 74 72 69 6e  |.this is a strin|
00000020  67 0d 0a 66 67 68 68 5f  68 6a 68 61 64 5f 74 65  |g..fghh_hjhad_te|
00000030  78 74 7b 09 74 65 78 74  20 61 66 74 65 72 20 62  |xt{.text after b|
00000040  72 61 63 65 20 77 69 74  68 20 74 61 62 0d 0a 0d  |race with tab...|
00000050  0a 7b 0d 0a 7b 20 74 65  78 74 20 20 61 74 20 20  |.{..{ text  at  |
00000060  20 20 65 6e 64 20 20 20  20 20 6f 6e 6c 79 2c 20  |  end     only, |
00000070  28 77 69 74 68 20 73 70  61 63 65 73 29 21 0d 0a  |(with spaces)!..|
00000080  61 62 63 64 5f 31 32 33  0d 0a 65 6e 64 20 6f 66  |abcd_123..end of|
00000090  20 66 69 6c 65 20 77 69  74 68 6f 75 74 20 62 72  | file without br|
000000a0  61 63 65 0d 0a                                    |ace..|
000000a5
cat /tmp/text:

abc def{
cdefg
this is a string
fghh_hjhad_text{    text after brace with tab

{
{ text  at    end     only, (with spaces)!
abcd_123
end of file without brace
TEST FILE CREATION END, FILTER START!

FILTER DONE!

00000000  61 62 63 20 64 65 66 7b  0d 0a 66 67 68 68 5f 68  |abc def{..fghh_h|
00000010  6a 68 61 64 5f 74 65 78  74 7b 09 74 65 78 74 20  |jhad_text{.text |
00000020  61 66 74 65 72 20 62 72  61 63 65 20 77 69 74 68  |after brace with|
00000030  20 74 61 62 0d 0a 7b 0d  0a 7b 20 74 65 78 74 20  | tab..{..{ text |
00000040  20 61 74 20 20 20 20 65  6e 64 20 20 20 20 20 6f  | at    end     o|
00000050  6e 6c 79 2c 20 28 77 69  74 68 20 73 70 61 63 65  |nly, (with space|
00000060  73 29 21 0d 0a                                    |s)!..|
00000065

abc def{
fghh_hjhad_text{    text after brace with tab
{
{ text  at    end     only, (with spaces)!
AMIGA:amiga~/Desktop/Code/Shell> _