sed

sed can be used to substitute
eg. substitute : with nothing, and do for every occurrence (represented by g) 

sed 's/://g'


s/X/Y/
replaces X with Y
/ represents nothing
g represents every occurance


remove multiple characters from line

Below removed [ and ] 

sed 's/[][]//g'
below removes , 7 and l 
sed 's/[,7l]//g'


remove anything before a character

sed 's/.*[/]//'
For example, if you are trying to get the log format for apache (centos): 
grep ^ErrorLog /etc/httpd/conf/httpd.conf | awk '{print $2}' | sed 's/.*[/]//'
Returns 
error_log
Sometimes format is error.log