Convert an input file from lower case to upper case

Question

I have a text file as "temp" with contents

Hai! How are you

I wanted to change the contents of the same file to

HAI! HOW ARE YOU

When i used cat temp |tr a-z A-Z (---only output was shown as upper case. The file remain unchanged....). I wanted the file contents to be changed. On Using cat temp |tr a-z A-Z>>temp (--the out was appended not overwritten). Kindly help

Welcome to SO, please try to wrap your samples in CODE TAGS a `{}` button in your post, also try to show your efforts too(in code tags only). — RavinderSingh13, Jul 09 '18 at 11:00

score 0 · Answer 1 · answered Jul 09 '18 at 10:59

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You can use a temporary file to store the result:

cat temp | tr "a-z" "A-Z" > t
rm temp
mv t temp

Using sed should also work:

sed -i 's/./\U&/g' temp

answered Jul 09 '18 at 10:59

Poshi

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Rene Knop · Answer 2 · 2018-07-09T12:11:32.587

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Read content from temp, convert it to upper case and write it back to temp:

echo "$(awk '{print toupper($0)}' < temp)" > temp

edited Jul 09 '18 at 12:11

answered Jul 09 '18 at 11:01

Rene Knop

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I believe same solution is given here too https://stackoverflow.com/a/51243990/5866580 :) cheers – RavinderSingh13 Jul 09 '18 at 11:02

score 0 · Answer 3 · answered Jul 09 '18 at 11:03

0

cat temp |tr a-z A-Z>>temp

will not overwrite becouse of double '>'

To overwrite content use single '>'

cat temp |tr a-z A-Z>temp

answered Jul 09 '18 at 11:03

Alex

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Thanks Adam. Using the above only makes change to the first character in the file. – anitha Jul 09 '18 at 11:09
Could You explain -1 vote? I am right about how cat outstream is working – Alex Jul 09 '18 at 13:27

Convert an input file from lower case to upper case

3 Answers3