Short way to escape HTML in Bash?

Question

The box has no Ruby/Python/Perl etc.

Only bash, sed, and awk.

A way is to replace chars by map, but it becomes tedious

Answer 1

Pure bash, no external programs:

function htmlEscape () {
    local s
    s=${1//&/&}
    s=${s//</&lt;}
    s=${s//>/&gt;}
    s=${s//'"'/&quot;}
    printf -- %s "$s"
}

Just simple string substitution.

Answer 2

or use xmlstar Escape/Unescape special XML characters:

$ echo '<abc&def>'| xml esc
&lt;abc&amp;def&gt;

Answer 3

You can use recode utility:

    echo 'He said: "Not sure that - 2<1"' | recode ascii..html

Output:

    He said: "Not sure that - 2<1"

Answer 4

Escaping HTML really just involves replacing three characters: <, >, and &. For extra points, you can also replace " and '. So, it's not a long sed script:

sed 's/&/\&amp;/g; s/</\&lt;/g; s/>/\&gt;/g; s/"/\&quot;/g; s/'"'"'/\&#39;/g'

Answer 5

The previous sed replacement defaces valid output like

<

into

<

Adding a negative loook-ahead so "&" is only changed into "&" if that "&" isn't already followed by "amp;" fixes that:

sed 's/&(?!amp;)/\&amp;/g; s/</\&lt;/g; s/>/\&gt;/g; s/"/\&quot;/g; s/'"'"'/\&#39;/g'