Final answer:
Grep wildcards include ., *, ?, and [ ].
Step-by-step explanation:
When using the grep command, there are several wildcards you can use to search for patterns in a text. Some of the common wildcards include:
- `.`: Matches any single character.
- `*`: Matches zero or more occurrences of the previous character.
- `?`: Matches zero or one occurrence of the previous character.
- `[ ]`: Matches any one character specified within the bracket.
For example, to search for all words starting with the letter 'a', you can use the command grep '^a' filename. To search for words ending with 'ing', you can use grep 'ing$' filename.