You need to find a pattern in a file. Using regular expression.
Normal command to display something in a file, is grep.
grep "pattern" filename
You can also display the line number it occured on (-n) and ignore case (-i):
grep -n -i "pattern" filename
Also you can match more than one pattern:
egrep "patternA|patternB" filename
To match the beginning of a line (^) or the end of line ($) – this will only match lines with this specific pattern on:
grep "^patternA$" filename
We can also use wildcards and ranges – this will match any line with PATTERN in it followed by any amount of numbers:
grep "^.*PATTERN[0-9]*$" filename
[tags]grep, regular expression, Unix Coding School[/tags]