Boyd Stephen Smith Jr. wrote:
In <878wkcdobs....@gmail.com>, Rodolfo Medina wrote:
Suppose that I want to remove all the packages beginning with `texlive',
that are a lot in my system.
If I do: `aptitude purge texlive*', the system complains that no package
has that name.
Right, the shell performs "globbing", matching such patterns against
pathnames and providing multiple arguments to the underlying command. As
packages aren't accessible via pathnames, you can't count on your shell
finding them.
How to do then?
Aptitude itself uses regular expressions (I like PCRE, might just be posix-
extended) to match against package properties paired with "atoms" or
"operators" (I can't remember the correct terminology) to select which
property or combine searches.
In this case use the aptitude search string "~n^texlive" or simply
"^texlive" since "~n" is the default.
Since these aptitude search expressions can have characters in them that the
shell interprets (e.g. *, ?, and [] all have special meaning in both regular
expressions and shell "glob"s), you'll want to surround the expression in
single-quotes to prevent the shell from interpreting it -- passing it
directly to aptitude after removing the quotes.
Something like:
aptitude purge '^texlive'
Of course, things get really confusing when they have special meanings
in both the shell and regexps, and you want to negate both of them.
Suppose I want to grep for a letter (f in this example) followed by the
asterisk in a file, I'd need to use this command:
grep f\\\* $file
grep f* $file would search for the name of any file in the current
directory beginning with f, in that file (or the below if no files begin
with f)
grep f\* $file would search for 0 or more occurences of the letter f in
that file (in other words, every line)
grep f\\* $file would search for the name of any file in the current
directory beginning with f\ in that file (or the below if no files begin
with f\)
grep f\\\* $file would search for an f followed by an asterisk.
And that gets even more confusing when you put it in C, in, for example,
a system() call:
system("grep f\\\\\\* $file");
(The backslashes are doubled up so that C does not interpret them as its
own escape characters, like \n). And if you wanted (for example) a
newline in the middle of that command, you would probably die from
confusion :p
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