Merge column from command output into a single row

Question

I am using dnf list installed to list all installed packages, which returns the following output:

zenity.x86_64                                                                         3.22.0-1.fc25                                                               @@commandline          
zip.x86_64                                                                            3.0-16.fc24                                                                 @@commandline          
zlib.i686                                                                             1.2.8-10.fc24                                                               @@commandline          
zlib.x86_64                                                                           1.2.8-10.fc24                                                               @@commandline          
zlib-devel.x86_64                                                                     1.2.8-10.fc24                                                               @@commandline          
znc.x86_64                                                                            1.6.5-1.fc25                                                                @@commandline 

I am only interested in names of the packages, i.e. the value of the first column but only until the . (e.g. znc.x86_64 -> znc).

How could I merge results from this command output into a single line separated with spaces (e.g. zip zlib zlib-devel znc)?

Answer 1

awk + sort solution:

dnf list installed | awk -F. -v ORS="\0" '{print $1" "}' | sort -zu && echo ""

The output should look like:

zenity zip zlib zlib-devel znc

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-v ORS="\0" - considering input as zero-terminated records

sort -zu - to get unique zero-terminated values