CODEWITHSUNDEEP
bashsed
Julien B.
Julien B.

Reputation: 3324

sed with complex string

I'm trying to sed into phpMyAdmin config file to add a blowfish key.

Here's what I have so far...

k=$(openssl rand -base64 32)
o="\$cfg['blowfish_secret'] = '';"
n="\$cfg['blowfish_secret'] = '$k';" 
sed -i -e 's/'"$o"'/'"$n"'/g' /var/www/phpmyadmin/config.inc.php

I don't get any error, but it's not working as expected.

echo -e "$k\n$o\n$n"

returns 

Jgcv3FlugcVi5rDYLCdNhxX6sEZatt0zTZV3PISiLJY=
$cfg['blowfish_secret'] = '';
$cfg['blowfish_secret'] = 'Jgcv3FlugcVi5rDYLCdNhxX6sEZatt0zTZV3PISiLJY=';

And...

cat /var/www/phpmyadmin/config.inc.php | grep blowfish

returns

$cfg['blowfish_secret'] = ''; /* YOU MUST FILL IN THIS FOR COOKIE AUTH! */

Please help!

Upvotes: 3

Views: 805

Answers (2)

Julien B.
Julien B.

Reputation: 3324

AS 123 mentioned in a comment [] characters were interpreted as character classes by sed, simply escaping it with backslash solved my problem.

So this :

k=$(openssl rand -base64 32)
o="\$cfg['blowfish_secret'] = '';"
n="\$cfg['blowfish_secret'] = '$k';" 
sed -i -e 's/'"$o"'/'"$n"'/g' /var/www/phpmyadmin/config.inc.php

Was changed to that :

k=$(openssl rand -base64 32)
o="\$cfg\['blowfish_secret'\] = '';"
n="\$cfg\['blowfish_secret'\] = '$k';" 
sed -i -e 's/'"$o"'/'"$n"'/g' /var/www/phpmyadmin/config.inc.php

And now it works.

EDIT :

Since openssl rand -base64 32 can generate a string with slashes, it's better to escape it right away. Also, I chose to use perl after all. Here's the corrected code:

k=$(openssl rand -base64 32 | sed 's,\/,\\/,g')
o="\$cfg\['blowfish_secret'\] = '';"
n="\$cfg\['blowfish_secret'\] = '$k';"
sudo perl -p -i -e "s/$o/$n/g" /var/www/phpmyadmin/config.inc.php

Upvotes: 2

anubhava
anubhava

Reputation: 785196

If you want to use all kind of special regex meta characters in search and replace strings here is a non-regex way of doing that using awk:

# utility function to format search and replace strings
frmt() {
   printf "\$cfg['blowfish_secret'] = '%s';" "$1"
}

# awk command to perform search and replace using plain text search
awk -v s="$(frmt "")" -v r="$(frmt "$k")" 'n=index($0, s) {
   print r substr($0, n+length(s))
}' /var/www/phpmyadmin/config.inc.php

PS: Note that above awk command doesn't do inline editing of the file. If you want to do that then use -i inline option available with gnu-awk as:

awk -i inline -v s="$(frmt "")" -v r="$(frmt "$k")" 'n=index($0, s) {
   print r substr($0, n+length(s))
}' /var/www/phpmyadmin/config.inc.php

Upvotes: 0

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