how to use osmconvert to convert osm to excel sheet or csv file

OSMconvert is not a filter. This means that all features will be converted.

To achieve your goal of having only certain features in your csv file, you will have to filter the csv file generated by osmconvert afterwards.

Also, the arguments to the --csv option of osmconvert are the tag keys you want to have in your csv file. If you want "amenity" and "name" columns in addition to id, lat and lon, you specify "@id @lon @lat amenity name", and then filter the CSV output.

For example:

./osmconvert addis.osm --all-to-nodes --csv="@id @lon @lat amenity name" --out-csv -o=outfile.csv

grep cafe outfile.csv > cafes.csv
grep restaurant outfile.csv > restaurants.csv
cat cafes.csv restaurants.csv > cafes_and_restaurants.csv

I have tried do a similar thing: convert a way in baikal.osm to baikal.csv . The problem is the order of nodes I get in .csv file. I used

osmconvert baikal.osm --all-to-nodes --csv="@lon @lat" > baikal.csv

I get nodes in wrong order. osmconvert do not read the second part of .osm file with <nd ref= ...

How to solve this?

You can also have closer look at the Java based tool OsmPoisPbf, which scans an OpenStreetMap file for nodes and areas (and relations) whose tags indicate them as POIs (points of interest) and extracts those into a comma separated file (CSV).