How to delete a specific line from a file, or all characters following a specific character using sed

If you want to search a file for a particular string, and then delete that line, use sed, like this:

sed -i "/_use_column_stats_for_function/d" init.ora

In bash, using the double quotation marks was the only way to make this work when using a variable instead of a fixed string.

To delete a specific line number, in this case line number 7:

 sed -i '7d' myfile.txt
 

To delete lines 7 and 8:

 sed -i '7,8d' insert_data.sql

To delete everything after a specific character, for example #:

sed -i "s/#.*//g" /tmp/autoupgrade.ora