Replacing Control Character in sed

Question

I need to replace all occurrences of the control character CTRL+A (SOH/ascii 1) in a text file in linux, how can this be achieved in SED?

Answer 1

You Can use tr command

tr -s '\001' '|' newfile

tr -s "word or delimiter" want to replace with "word or delimiter" newfile

Answer 2

This can be done through cat with the -v (equivalently --show-nonprinting options and piping this into sed).

If the control character the start of heading (SOH) character (CTRL+A / ASCII 1), and we want to replace it with a tab, we would do the following:

cat -v file | sed 's/\^A/\t/g' > out

cat -v would replace the SOH character with ^A, which would then be matched and replaced in sed.

Answer 3

What do you want to replace them with? If the replacement is a single character, tr is a better choice than sed. To replace with the letter 'a':

tr '\1' a < input-file > tmp && mv tmp input-file

Answer 4

By "replace", I'm assuming you want to change the file 'in-place'.

Using GNU sed:

# Create a file with a single control character (SOH)
echo -e "\x01" > file
# Change SOH control characters to the literal string "SOH"
sed -i 's/\x01/SOH/g' file
# Check result
cat file

gives...

SOH

The -i option doesn't work on OS X sed, so you'd need to work-around that by piping sed to a temporary file.

Answer 5

Try:

sed 's/^A/foo/g' file

Use Ctrl+V+A to create the ^A sequence in the above command.