Ytdyklly

I'm on system running a (fairly recent-)Debian-based distribution.

I'd like to generate a plain list of all installed packages matching a certain pattern. I can do that by, running, say,

apt list --installed "linux-image-*" | cut -d/ -f1

but I get lines I don't care for, e.g.:

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.



Listing...

So maybe I'd better not use apt. I can run dpkg-query like so:

dpkg-query --showformat='${Package}n' --show "linux-image*"

but that's not limited to installed packages. I could use

dpkg-query --list "linux-image-*" | grep "ii"

but then I'd need to do a bunch of text processing, and who can trust those spaces, right?

So, bottom line: What's the right way to get the list of installed packages matching a pattern?

Note:

• Bonus points if it can be a proper regexp rather than just a shell glob.


• Having to parse the text seems like a less-than-ideal solution; if that's what you suggest, please argue why there isn't a better way.

aptitude supports searching among all packages known to the package management tools, installed or otherwise, using regular expressions, without extraneous output, and can be told how to format its output:

aptitude search "linux-image-.*"

To list only installed packages:

aptitude search "linux-image-.* ~i"

To list only installed package names matching the regular expression:

aptitude search "linux-image-.* ~i" -F "%p"

The documentation covers the available search patterns and output format specifiers in detail. You’ll also find examples on this site, for example is there a way to use regexp with aptitude?, regexp with aptitude part 2, and Linux - display or upgrade security updates only using apt.

Here's one good way to do get the list of installed packages on a Debian-based system:

dpkg -l | grep ^ii | awk '{print $2}'

The output lines of dpkg -l can be trusted to be sane.
The pattern ^ii will match the lines of installed packages,
and the simple Awk will extract the second column,
the package names (the same names used in apt-get install commands).
Package names cannot contain whitespace,
so this again is a safe operation.

$ apt list --installed "linux-image-*" 2>/dev/null |awk -F'/' 'NR>1{print $1}'

linux-image-3.16.0-4-amd64

linux-image-4.11.0-1-amd64

linux-image-4.12.0-1-amd64

linux-image-4.13.0-1-amd64

linux-image-4.8.0-2-amd64

linux-image-4.9.0-1-amd64

linux-image-4.9.0-2-amd64

linux-image-4.9.0-3-amd64

Talking about regex:

$ apt list --installed "linux-image-*" 2>/dev/null |awk -F'/' 'NR>1 && $0~/4.1/{print $1}'

linux-image-4.11.0-1-amd64

linux-image-4.12.0-1-amd64

linux-image-4.13.0-1-amd64

You can also use dpkg-query with -f (--showformat) option,which when invoked without any package name, by default only installed packages are listed.

$ dpkg-query -f '${Package}n' -W |grep 'linux-image' #-W == --show

In order to "trap" the searched term when grep ping dpkg output, need to encase the search term as follows. "git" is used as the specimen search term:

dpkg -l |grep "^ii  git[[:space:]]"

The carat (^) ii followed by (2) spaces prepending the searched term ensures nothing BEFORE it other than that combination of characters can match.

The [[:space:]] abutting the searched term precludes partial matches from occurring by only matching spaces immediately AFTER it.