Linux command to extract a text

Question

Text:

All rights reserved. ERROR: ORA-00257: archiver error. Connect internal only, error. SP2-0751: Unable to connect to oracle. Exiting SQL*Plus

My intended output:

ERROR: ORA-00257: archiver error.

My command:

sed 's/.*\(ERROR:.*\.\).*/\1/'

Actual Output:

ERROR: ORA-00257: archiver error. Connect internal only, error. SP2-0751: Unable to connect to oracle.

How can i tweak my sed command to display only this:

ERROR: ORA-00257: archiver error.

Answer 1

不要取所有字符（ .* ）后接点，而应取“除点之外的所有字符”（ [^\\.]* ）后接点：

sed 's/.*\(ERROR:[^\.]*\.\).*/\1/'

Answer 2

Sed use greedy match by default and it seems that sed doesn't support non-greedy match, so it will match as long as possible.

You can change .*\\. in the parenthesis into [^.]*\\. to match a non-dot character then follow a dot, this should behave like non-greedy match. Or you can use a more powerfull regex engine like perl:

perl -pe 's/.*(ERROR:.*?\\.).*/\\1/'

Answer 3

You can achieve the same with sed

$ sed -r 's/.*(ERROR[^.]*\.).*/\1/' log

ERROR: ORA-00257: archiver error.