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I use the following grep query to find the occurrences of functions in a VB source file.
grep -nri "^\s*\(public\|private\|protected\)\s*\(sub\|function\)" formName.frm
This matches -
Private Sub Form_Unload(Cancel As Integer)
Private Sub lbSelect_Click()
...
However, it misses out on functions like -
Private Static Sub SaveCustomer()
because of the additional word "Static" in there. How to account for this "optional" word in the grep query?
226
The '?' after the '(administratively )' capture group, basically tells the regex that the previous group/character is optional.
The ' \ ' character, when followed by certain ordinary characters, takes a special meaning: ' \b ' Match the empty string at the edge of a word. ' \B ' Match the empty string provided it's not at the edge of a word.
GNU grep supports three regular expression syntaxes, Basic, Extended, and Perl-compatible. In its simplest form, when no regular expression type is given, grep interpret search patterns as basic regular expressions. To interpret the pattern as an extended regular expression, use the -E ( or --extended-regexp ) option.
The wildcard * (asterisk) can be a substitute for any number of letters, numbers, or characters. Note that the asterisk (*) works differently in grep. In grep the asterisk only matches multiples of the preceding character. The wildcard * can be a substitute for any number of letters, numbers, or characters.
You can use a \? to make something optional:
grep -nri "^\s*\(public\|private\|protected\)\s*\(static\)\?\s*\(sub\|function\)" formName.frm
In this case, the preceding group, which contains the string "static", is optional (i.e. may occur 0 or 1 times).
183
When using grep, cardinality wise :
* : 0 or many
+ : 1 or many
? : 0 or 1 <--- this is what you need.
Given the following example (where the very word stands for your static) :
I am well
I was well
You are well
You were well
I am very well
He is well
He was well
She is well
She was well
She was very well
If we only want
I am well
I was well
You are well
You were well
I am very well
we'll use the '?' (also notice the careful placement of the space after 'very ' to mention that we'll want the 'very' word zero or one time :
egrep "(I|You) (am|was|are|were) (very )?well" file.txt
As you guessed it, I am inviting you to use egrep instead of grep (you can try grep -E, for Extended Regular Expressions).
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