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An Ignorant Wanderer
Asked: 2020-07-07 13:53:50 +0800 CST

Trying to add an ampersand at the end of every line of file using sed

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I am trying to add an ampersand at the end of every line of a file using sed as follows:

sed -i -e 's/$/ &/' file

However, when I look at the contents of the file (using both Vim and just cating the file) I don't see the ampersand (only an extra space). I tried with another character 'l' and it worked. Why doesn't it work with ampersand?

command-line sed

1 Answers

  1. Best Answer

    & is one of very few characters that is special on the replacement side of a sed s/pattern/replacement/ command - in particular, it is replaced by the whole matched portion of the pattern space. In this case, the whole matched portion is a zero length assertion $, so & appears to insert nothing in the replacement.

    To add a literal ampersand, you therefore need to escape it:

    sed -i -e 's/$/ \&/' file
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