CODEWITHSUNDEEP
bashsedprintf
zagortenay333
zagortenay333

Reputation: 259

Bash: printf and sed

I cannot wrap my head around this...

Why does this construct not work:

printf -v REGEX "%s\\|" "string1" "string2"
REPLACE="blabla"

sed "s/${REGEX}/${REPLACE}/" file1 > file2

But this works:

REGEX="string1\|string2\|"
REPLACE="blabla"

sed "s/${REGEX}/${REPLACE}/" file1 > file2

printf creates the same string as the one in the second example, yet sed cannot substitute it. Instead, it places the REPLACE string at the beginning of every line in file2.

Upvotes: 0

Views: 2564

Answers (1)

Charles Duffy
Charles Duffy

Reputation: 295687

Consider instead:

printf -v regex '%s|' string1 string2
sed -r -e "s/${regex%|}/$replace/" file1 > file2

This works because it removes the trailing | from the regex, preventing it from matching the empty string.

Upvotes: 2

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