UNIX for Beginners Questions & Answers

awk '/----\r$/ && $1=$1' OFS=, /tmp/sample_linebyline.txt 
840-1,1,ABCD,0010211-00,0012345678/012345678912,123456789012,2745.25-,----
840-1,1,ABCD,0010211-00,0012345678/012345678912,123456789012,2745.25,----

awk '/---- *\r$/ && $1=$1' OFS=, /tmp/flatfile_sample.txt 
840-1,1,ABCD,0010211-00,0012345678/012345678912,123456789012,2745.25-,----,
840-1,1,ABCD,0010211-00,0012345678/012345678912,123456789012,2745.25,----,

with open('sample_linebyline.txt') as rf, open('sample_linebyline.csv', 'w') as wf:
    for line in rf:
        if line.endswith('----\n'):
            fields = line.split()
            print(",".join(fields), file=wf)

with open('flatfile_sample.txt') as rf, open('flatfile_sample.csv', 'w') as wf:
    for line in rf:
        if '----' in line:
            fields = line.split()
            print(",".join(fields), file=wf)

$ cat sample_linebyline.csv
840-1,1,ABCD,0010211-00,0012345678/012345678912,123456789012,2745.25-,----
840-1,1,ABCD,0010211-00,0012345678/012345678912,123456789012,2745.25,----

$ cat flatfile_sample.csv
840-1,1,ABCD,0010211-00,0012345678/012345678912,123456789012,2745.25-,----
840-1,1,ABCD,0010211-00,0012345678/012345678912,123456789012,2745.25,----

awk 'BEGIN {OFS=","} {print $1,$2,$3,$4,$5,$6,$7,$8}' D:/tmp/file > tmp.txt
awk '/----/' D:/tmp/tmp.txt >tmp1.txt

file /tmp/flatfile_sample.txt 
/tmp/flatfile_sample.txt: ASCII text, with very long lines, with CRLF line terminators