If you wish to find strings at the end of a line that don't end with a particular character, you can use a bracket expresion with a caret character after the left square bracket in a regular expression.
| Metacharacter | Description |
|---|---|
| [^ ] | Matches a single character that is not contained within the brackets. For example, [^abc] matches any character other than "a", "b", or "c". [^a-z] matches any single character that is not a lowercase letter from "a" to "z". Likewise, literal characters and ranges can be mixed. |
E.g., suppose I have file named list.txt containing the following words:
coat
cop
core
coaster
clam
chrome
counter
cure
claustrophobia
closet
If I wanted to find only those lines that don't end with either the letter
"e", "r", or "t", I could use the regular expression [^ert]$
for a grep
search as shown below:
$ grep '[^ert]$' list.txt cop clam claustrophobia $
The dollar sign at the end of the regular express indicates that I'm looking for the pattern at the end of the line.
| Metacharacter | Description |
|---|---|
| $ | Matches the ending position of the string or the position just before a string-ending newline. In line-based tools, it matches the ending position of any line. |
I receive a
spreadsheet every month containing over a thousand email
addresses that I need to validate. I
extract the column
containing the email addresses from the spreadsheet to a text file with a Python
script. Most of the email addresses end with .com, though
there are also .gov and .net addresses. Occasionally the "m" has been mistyped
as an "n", so I can search for any email addresses that have some other
character after ".co" in the
Vi text
editor with the regular expression /\.co[^m]\n.
The backslash
before the period is needed to
"escape"
the normal
metacharacter meaning of the period, which otherwise in a regular
expression (regexp) represents any character. The \n
represents the
newline character, i.e., the end of the line. I could also type a slash
followed by \.[^m]\$ in Vi, since the dollar sign represents
the end of the line. For a grep search, though, I need to use the dollar
sign at the end of the regular expression.
$ grep '\.co[^m]$' email_list.txt john.doe@example.con $