Sed - Lower case single characters

zlindner · #1 (**permalink**) 04-28-2005

Hello,

I have a file where I am supposed to convert all the single i characters to uppercase, but when I try, it converts all the i's inside of words to uppercase as well.

I tried doing:

cat filename | sed 's/i/I/g'

but that obviously does not work.

Any help would be greatly appreciated.

Thanks.

bhargav · #2 (**permalink**) 04-28-2005

Code:


$ cat file1
i am unix guy
$ sed 's/i /I/g' file1
Iam unix guy
$

ramkrix · #3 (**permalink**) 12-07-2007

sed 's/ i / I /g'

Single space prefixed and suffixex with both upper and lower case I

Please reply back whether it works or not

Franklin52 · #4 (**permalink**) 12-08-2007

Quote:

Originally Posted by ramkrix

sed 's/ i / I /g'

Single space prefixed and suffixex with both upper and lower case I

Please reply back whether it works or not

It's not as easy as it seems, what if you have a file like this?

i'm the big brother.
i never drink water, i
only drink beer.
i've got to do this job.
Yes, i can do it.

There should be more possibilities but try this one:

Code:

sed -e 's/i/I/g' -e 's/\([a-zA-Z].*\)I\([a-zA-Z].*\)/\1i\2/g' file

Regards

drl · #5 (**permalink**) 12-08-2007

Hi.

Using the boundary assertions of regular expressions as gus2000 mentioned:

Code:

#!/usr/bin/env sh

# @(#) s1       Demonstrate changing case considering "word" boundaries.

set -o nounset
echo

debug=":"
debug="echo"

## Use local command version for the commands in this demonstration.

echo "(Versions displayed with local utility \"version\")"
version >/dev/null 2>&1 && version bash sed

echo

FILE=${1-data1}
echo " Input file:"
cat $FILE

echo
echo " Results from sed:"
sed 's_\<i\>_I_g' $FILE

exit 0

Producing:

Code:

% ./s1

(Versions displayed with local utility "version")
GNU bash 2.05b.0
GNU sed version 4.1.2

 Input file:
i'm the big brother.
i never drink water, i
only drink beer.
i've got to do this job.
Yes, i can do it.

 Results from sed:
I'm the big brother.
I never drink water, I
only drink beer.
I've got to do this job.
Yes, I can do it.

This might vary with your version of sed, but I think it's fairly standard ... cheers, drl

ramkrix · #6 (**permalink**) 12-09-2007

Thanks Franklin for pointing out what I missed. But let me check the command with my solaris m/c. As its my week end here I cant access my m/c which is my office.

gus2000 · #7 (**permalink**) 12-08-2007

Well you can specify regex "word delimiters":

Code:

/\bWORD\b/                          # word is framed by blanks
/\<WORD\>/                          # match whole word inside < >
/[[:blank:]]WORD[[:blank:]]/        # word is framed by blanks (alternate)

Your choices will vary with your Unix distro and sed version.

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