The command below will return the corresponding strings
$ docker-compose exec postgres postgres --version
postgres (PostgreSQL) 10.4 (Debian 10.4-2.pgdg90+1)
I am trying to get the postgresql version but when I tried, the Debian version and other numbers are included like
$ pg_version=$(docker-compose exec postgres postgres --version | sed 's/[^0-9.]//g')
10.410.42.901
I am wondering how to get the 10.4 only
awk -v RS=" " '/^[0-9.]+$/{print; exit}'grep -oE '[.0-9]+' | head -1tr ' ' '\n' | grep -oE -m 1 '[.0-9]+'sed 's|^[^0-9.]*\([0-9.]\+\).*|\1|'Modify the sed as followed would help,
sed -E 's/.*PostgreSQL[^0-9.]+([0-9.]*).*/\1/'
\1 would only match to the version number right behind "PostgreSQL".
pg_version=$(docker-compose exec postgres postgres -V | grep -oE '[.0-9]+' | head -1)
10.4 10.4. This value returned. How to return only one 10.4?
head -1 to print first one.
[.0-9]+ would be sufficient in this case. BTW, it's better to write it as grep -oE, since egrep is deprecated.You could use grep with something like this:
$ grep -oP "PostgreSQL.\s\K.+?(?=\s)"
For example:
$ echo "postgres (PostgreSQL) 10.4 (Debian 10.4-2.pgdg90+1)" | grep -oP "SQL.\s\K.+?(?=\s)"
10.4
The \K can be read as excluding everything to the left *SQL)<space> before it and return only the right part .+?(?=\s) until and space \s is found.
10.4 (Debian 10.4-2.pgdg90+1)