Grep pattern matching lower case string enclosed in double quotes

Question

I'm having a bit of an issue with grep that I can't seem to figure out. I'm trying to search for all instances of lower case words enclosed in double quotes (C strings) in a set of source files. Using bash and gnu grep: ``` grep -e '"[a-z]+"' *.cpp ``` gives me no matches, while ``` grep -e '"[a-z]*"' *.cpp ``` gives me matches like "Abc" which is not just lower case characters. What is the proper regular expression to match only "abc"?

Accepted Answer

You're forgetting to escape the meta characters.

```
grep -e '"[a-z]\+"'
```

For the second part, the reason it is matching multi-case characters is because of your locale. As follows:

```
$ echo '"Abc"' | grep -e '"[a-z]\+"'
"Abc"
$ export LC_ALL=C
$ echo '"Abc"' | grep -e '"[a-z]\+"'
$
```

To get the "ascii-like" behavior, you need to set your locale to "C", as specified in the grep man page:

Within a bracket expression, a range expression consists of two characters separated by a hyphen. It matches any single character that sorts between the two characters, inclusive, using the locale's collating sequence and character set. For example, in the default C locale, [a-d] is equivalent to [abcd]. Many locales sort characters in dictionary order, and in these locales [a-d] is typically not equivalent to [abcd]; it might be equivalent to [aBbCcDd], for example. To obtain the traditional interpretation of bracket expressions, you can use the C locale by setting the LC_ALL environment variable to the value C.

Grep pattern matching lower case string enclosed in double quotes

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