Shell Programming and Scripting

Hi,

I have a file that looks like the following:

M00071.null T
12 13 1 0 0
SMALL
M00074.null T 1
15 14 0 0 0
SMALL
M14870.null T 2 15431
15 17 0 1 0
SMALL

I want to edit it such that it looks like the following:

M00071
12 13 1 0 0
SMALL
M00074
15 14 0 0 0
SMALL
M14870
15 17 0 1 0
SMALL

So basically any line that begins with M and has .null in it (M00074.null T 1) is replaced with M followed by the number (M00074)


I can easily extract data and do it :

awk /.null/ filename | cut -d '.' -f1

Looking for help to search and replace in the same file.
Thanks in advance.

Code:

echo 'M00071.null T' | sed 's#^\(M[0-9][0-9]*\)[.]null.*#\1#'

> cat m0
M00071.null T
12 13 1 0 0
SMALL
M00074.null T 1
15 14 0 0 0
SMALL
M14870.null T 2 15431
15 17 0 1 0
SMALL

> cat m0 | cut -d"." -f1 >m1 ;cp m1 m0
> cat m0
M00071
12 13 1 0 0
SMALL
M00074
15 14 0 0 0
SMALL
M14870
15 17 0 1 0
SMALL


of course, I still need to get rid of the m1 temporary file
Note: I normally do not like to do all in one line for the chance of something wrong with the script might corrupt the original data.

vgersh99 : i dont really understand why i need to do

echo 'M00071.null T'

when i want to change all instances of .null in the file


joeyg your solution wont work for me because my file has more data that i didnt show which has "." in it.


As i mentioned i need to search for lines that contain ".null" and then remove everything after the "." in that line.

mjoshi,
my original post showed a sed's regex to deal with the pattern you specified.
take the 'sed' and apply it to the file.

vgersh99 : oops i get it , the echo command was meant to show me it works on the first case ('M00071.null T' ).

The sed command indeed works for my case. Thanks !