UNIX for Beginners Questions & Answers

1234
1234
1234

aaaa
bbbb
cccc
dddd

cat file1.txt file2.txt > file3.txt

1234
1234
1234
aaaa
bbbb
cccc
dddd

{ cat file1; echo; cat file2; } > file3

for file in "$@"
do	tr -d '\r' "$file"
	echo
done

sh merge file1.txt file2.txt > file3.txt

#!/bin/sh
# All longhand to see the sequence of events.

echo "Create files as per OP."
printf "1234\r\n1234\r\n1234" > /tmp/file1.txt
printf "aaaa\r\nbbbb\r\ncccc\r\ndddd" > /tmp/file2.txt
echo "Join together to test."
cat /tmp/file1.txt /tmp/file2.txt > /tmp/file3.txt
cat -v /tmp/file3.txt
echo ""
echo "Remove ^M, <CR> character and create temp files 4 and 5..."
tr -d '\r' < /tmp/file1.txt > /tmp/file4.txt
tr -d '\r' < /tmp/file2.txt > /tmp/file5.txt
cat /tmp/file4.txt /tmp/file5.txt > /tmp/file3.txt
echo "...and check the error exists."
cat -v /tmp/file3.txt
echo ""
echo "Now add the newlines in the correct place, longhand."
cat /tmp/file4.txt > /tmp/file3.txt
echo "" >> /tmp/file3.txt
cat /tmp/file5.txt >> /tmp/file3.txt
echo "" >> /tmp/file3.txt
echo "Finalisation."
cat /tmp/file3.txt
echo "Check file validity using 'hexdump'."
hexdump -C /tmp/file3.txt

Last login: Tue May 29 17:17:20 on ttys000
AMIGA:barrywalker~> cd Desktop/Code/Shell
AMIGA:barrywalker~/Desktop/Code/Shell> chmod 755 CATFiles.sh
AMIGA:barrywalker~/Desktop/Code/Shell> ./CATFiles.sh
Create files as per OP.
Join together to test.
1234^M
1234^M
1234aaaa^M
bbbb^M
cccc^M
dddd
Remove ^M, <CR> character and create temp files 4 and 5...
...and check the error exists.
1234
1234
1234aaaa
bbbb
cccc
dddd
Now add the newlines in the correct place, longhand.
Finalisation.
1234
1234
1234
aaaa
bbbb
cccc
dddd
Check file validity using 'hexdump'.
00000000  31 32 33 34 0a 31 32 33  34 0a 31 32 33 34 0a 61  |1234.1234.1234.a|
00000010  61 61 61 0a 62 62 62 62  0a 63 63 63 63 0a 64 64  |aaa.bbbb.cccc.dd|
00000020  64 64 0a                                          |dd.|
00000023
AMIGA:barrywalker~/Desktop/Code/Shell> _