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Replace specific letter in a file by other letter

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# 1  
Old 05-13-2015
Replace specific letter in a file by other letter
Good afternoon all,
I want to ask how to change some letter in my file with other letter in spesific line

eg.
data.txt
Code:
1
1
1
0
0
0
0

for example i want to change the 4th line with character 1.
How could I do it by SED or AWK.

I have tried to run this code but actually did not modify the data.txt file and just print the result to screen.
Code:
sed -e "4s/0/1/" data.txt

# 2  
Old 05-13-2015
That's how it works. Redirect the output to a temp file and then, mv the temp file to data.txt, overwriting it.
# 3  
Old 05-13-2015
Or, use ed instead of sed:
Code:
ed data.txt <<-EOF
	4s/0/1/
	w
	q
EOF

or:
Code:
printf '%s\n' '4s/0/1' w q | ed data.txt

# 4  
Old 05-15-2015
With GNU sed and BSD sed, there is the -i option for in-place editing, but there the recommend option is to have it automatically create a backup file as well..
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