如何过滤linux中的目录文件

Question

How to display the types of all the files in the personal directory in home directory
that:

1. do not start with certain letters like a , k
2. and the third letter in their name is not a digit and not a letter (upper or lower case)

Answer 1

Try grep with regular expressions:

ls -1 | grep -ve "^a\|^k\|^..[0-9]\|^..\w" | cut -d . -f 2

-v : veto matches -e : use regular expressions

The -1 is to make sure that you don't have several files in one line.

The regular expression means:

1. ^a\\|^k : no a or k at the beginning
2. ^..[0-9] : no number at the third position ( . is a wildcard for one position)
3. ^..\\w : no word (character or _ ) at the third position.

It's a bit longer but I'd consider it as a goog way to dive into regular expressions. For more details about regular expressions look for example here .

The cut command looks for the delimiter . and prints the second part of it ( -f 2 ).

Answer 2

If by "types" you mean extensions:

$ ls | egrep '^[^ak].[^a-zA-Z0-9]' | sed -e s/.*\\.//

There are shorthands for [^a-zA-Z0-9] but this one is easy to understand and adapt.