Shell Programming and Scripting

Hi ,
I've the following file names and i need the part of the file name
The files are like below

Code:

FN_DATE_TODAY_20010178654321.txt
FN_DATE_LASTDAY_19990178654321.txt

and i need to cut the filenames like below

Code:

FN_DATE_TODAY
FN_DATE_LASTDAY

How can i achieve that
Thanks

Use parameter substitution:

Code:

file="FN_DATE_TODAY_20010178654321.txt"
echo "${file%_*}"

Assuming that you're using a shell that performs the standard parameter expansions, the following script shows one way to do what you want:

Code:

for i in FN*
do      printf "%s cuts down to %s\n" "$i" "${i%_*}"
done

which (if the only two files in the current directory having filenames starting with FN are the two you listed), produces the output:

Code:

FN_DATE_LASTDAY_19990178654321.txt cuts down to FN_DATE_LASTDAY
FN_DATE_TODAY_20010178654321.txt cuts down to FN_DATE_TODAY

Hello,

Assuming that you have 18 characters after your file name including digits and .txt extension.

Code:

 
ls -ltr | grep -i "FN*" > test
 
cat test| awk '{for(i=0;i<=NF;i++) sub(/...................$/,X,$i)}1'
FN_DATE_TODAY
FN_DATE_LASTDAY

Hope it may help you.


Thanks,
R. Singh

You got yourself the Useless Use of Cat Award

The purpose of cat is to concatenate, awk is capable of reading file by itself, so no need to cat and pipe the output to awk.

There's a lot more wrong with that code than the relatively benign useless use of cat.

Why is ls using a long listing if only the filenames are of interest? Why is it doing a reverse mtime sort?

The grep regular expression is incorrect for two reasons: (1) it is unanchored, allowing the FN* to match anywhere and not just at the beginning, and (2) it applies a wildcard to N, so any filename with an F matches.

I haven't tested it, but I don't see how applying sub() to each field of a long ls listing generates the output shown.

I see no reason to bother with a temp file.

I think the shell solutions suggested above are just fine. However, if for some reason ls and grep are preferred:

Code:

ls | grep '^FN_' | cut -d_ -f1-3

With sed:

Code:

ls | sed '/^FN_/!d; s/_[^_]*$//p'

Regards,
Alister