grep matching but not printing if line end in dos ^M - regex

Question

I need to search in multiple files for a PATTERN, if found display the file, line and PATTERN surrounded by a few extra chars. My problem is that if the line matching the PATTERN ends with ^M (CRLF) grep prints an empty line instead.
Create a file like this, first line "a^M", second line "a", third line empty line, forth line "a" (not followed by a new line).
a^M
a
a
Without trying to match a few chars after the PATTERN all occurrences are found and displayed:
# grep -srnoEiI ".{0,2}a" *
1:a
2:a
4:a
If I try to match any chars at the end of the PATTERN, it prints an empty line instead of line one, the one ending in CRLF:
# grep -srnoEiI ".{0,2}a.{0,2}" *
2:a
4:a
How can I change this to act as expected ?
P.S. I will like to fix this grep, but I will accept other solutions for example in awk.
EDIT:
Based on the answers below I choose to strip the \r and force grep to pipe the colors to tr:
grep --color=always -srnoEiI ".{0,2}a.{0,2}" * | tr -d '\r'

Answer 1

Here's a simpler case that reproduces your problem:
# Output
echo $'a\r' | grep -o "a"
# No output
echo $'a\r' | grep -o "a."
This is beacuse the ^M matches like a regular character, and makes your terminal overwrite its output (this is purely cosmetic).
How you want to fix this depends on what you want to do.
# Show the output in hex format to ensure it's correct
$ echo $'a\r' | grep -o "a." | od -t x1 -c
0000000 61 0d 0a
a \r \n
# Show the output in visually less ambiguous format
$ echo $'a\r' | grep -o "a." | cat -v
a^M
# Strip the carriage return
$ echo $'a\r' | grep -o "a." | tr -d '\r'
a

Answer 2

awk -v pattern="a" '$0 ~ pattern && !/\r$/ {print NR ": " $0}' file
or
sed -n '/a/{/\r$/!{=;p}}' ~/tmp/srcfile | paste -d: - -
Both of these do: find the pattern, see if the line does not end in a carriage return, print the line number and the line. For the sed, the line number is on its own line, so we have to join two consecutive lines with a colon.

Answer 3

You could use pcregrep:
pcregrep -n '.{0,2}a.{0,2}' inputfile
For your sample input:
$ printf $'a\r\na\n\na\n' | pcregrep -n '.{0,2}a.{0,2}'
1:a
2:a
4:a

Answer 4

A couple more ways:
Use the dos2unix utility to convert the dos-style line endings to unix-style:
dos2unix myfile.txt
Or preprocess the file using tr to remove the CR characters, then pipe to grep:
$ tr -d '\r' < myfile.txt | grep -srnoEiI ".{0,2}a.{0,2}"
1:a
2:a
4:a
$
Note dos2unix may need to be installed on whatever OS you are using. More than likely tr will be available on any POSIX-compliant OS.

Answer 5

You can use awk with a custom field separator:
awk -F '[[:blank:]\r]' '/.{0,2}a.{0,2}/{print FILENAME, NR, $1}' OFS=':' file
TESTING:
Your grep command:
grep -srnoEiI ".{0,2}a.{0,2}" file|cat -vte
file:1:a^M$
file:2:a$
file:4:a$
Suggested awk commmand:
awk -F '[[:blank:]\r]' '/.{0,2}a.{0,2}/{print FILENAME, NR, $1}' OFS=':' file|cat -vte
file:1:a$
file:2:a$
file:4:a$