To match the pattern "pat" at the beginning of a line using the grep
command, the symbol ^
will be used.
Now let's go through each option and explain why it is right or wrong:
A. ^pat: This option is correct. The ^
symbol in a regular expression is used to match the pattern at the beginning of a line. Therefore, ^pat
will match the pattern "pat" at the beginning of a line.
B. $pat: This option is incorrect. The $
symbol in a regular expression is used to match the pattern at the end of a line. Therefore, $pat
will match the pattern "pat" at the end of a line, not at the beginning.
C. pat$: This option is incorrect. The $
symbol in a regular expression is used to match the pattern at the end of a line. Therefore, pat$
will match the pattern "pat" at the end of a line, not at the beginning.
D. pat^: This option is incorrect. The symbol ^
does not have any special meaning when it appears after the pattern. Therefore, pat^
will match the literal string "pat^" rather than the pattern "pat" at the beginning of a line.
The Answer is: A. ^pat