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loops with tr


 
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# 1  
Old 08-24-2009
loops with tr

Hello,

I'm not sure if this is more appropriate for the 'unix for dummies' or the 'unix for experts' forum because I'm new to this forum and this is the second topic I've discussed, but if you could let me know which one was more appropriate for something like this, please do!

So in tr (an ancient UNIX application), I can join all lines of a text file into one line by doing this:

Code:
tr -d '\n' <x >y

where x is the original file name with extension, and y is the new one.

This is about 10^6 times faster than the command %join! in vi, and doesn't leave a '\n' at the end.

-------------------
My question is, how to do this in a loop, say for all files beginning with a, and keep the filenames the same.
The following doesn't work:

Code:
for file in a*; do tr -d '\n' <"$file" >"$file"; done

This just turns a* into blank files.


I have a feeling that the problem is with the "$file" part, since tr might have a different format for the file name, but I'm not so familiar with tr

If anyone knows a way around this I would be very thankful Smilie
Thanks in advance!
# 2  
Old 08-24-2009
Code:
for file in "a*"
do 
   tr -d '\n' <"$file" >"${file}_new"
done

This code generate a new file for every file tha find, if you don't want the original file and you want to manteint the name of the file
Code:
for file in "a*"
do 
   tr -d '\n' <"$file" >"${file}_new"
   mv "${file}_new" $file
done

# 3  
Old 08-24-2009
Thank you very much chipcmc!

This worked perfectly once I removed the quotations around a* in your code,
Having the quotes there gave me error messages, maybe I have a different version of UNIX than you.

But nonetheless, your idea got the job done!
THanks so much Smilie
 

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