Find by regex and replace match to lowercase in Bash -

i replace contents of file match given regex lowercase equivalent. like:

grep -o '[^ ]*[a-z][^ ]*.png' file-21-05-2013.sql* | awk '{print tolower($0)}' 

the line above finds strings in given file have @ least 1 uppercase character , prints lowercase equivalent.

i replace output of grep command output of whole command above

does make sense?

if using gnu system gnu sed has following extension:

\l turn replacement lowercase until \u or \e found,  

the following command should need:

sed  "s/\([^ ]*[a-z][^ ]*.png\)/\l\1/g" file-21-05-2013.sql*