You can use a wildcard in the file pattern with grep, but not in the search pattern. The wildcard can be used to match multiple files. For example, grep "searchterm" *.log would search for “searchterm” in all .log files in the current directory.

However, grep does not support wildcards in the search pattern itself. If you want to search for a pattern that can have multiple forms, you can use regular expressions. For example, grep "error[0-9]*" file.log would search for “error” followed by any number of digits in file.log.

If you want to use a wildcard in the search pattern, you can use the -E option for extended regular expressions:

grep -E 'pattern.*' file

This will match any line that starts with ‘pattern’ followed by any characters. Note that in regular expressions, . matches any single character and * means “zero or more of the preceding element”.