Issue
I need to get the java version number, for example "1.5", from python (or bash).
I would use:
os.system('java -version 2>&1 | grep "java version" | cut -d "\\\"" -f 2')
But that returns 1.5.0_30
It needs to be compatible if the number changes to "1.10" for example.
I would like to use cut or grep or even sed. It should be in one line.
Solution
Considering an output like this:
$ java -version
java version "1.8.0_25"
Java(TM) SE Runtime Environment (build 1.8.0_25-b17)
Java HotSpot(TM) 64-Bit Server VM (build 25.25-b02, mixed mode)
You can get the version number with awk like this:
$ java -version 2>&1 | awk -F[\"_] 'NR==1{print $2}'
1.8.0
Or, if you just want the first two .-separated digits:
$ java -version 2>&1 | awk -F[\"\.] -v OFS=. 'NR==1{print $2,$3}'
1.8
Here, awk sets the field separator to either " or _ (or .), so that the line is sliced in pieces. Then, it prints the 2nd field on the first line (indicated by NR==1). By setting OFS we indicate what is the output field separator, so that saying print $2, $3 prints the 2nd field followed by the 3rd one with a . in between.
To use it in Python you need to escape properly:
>>> os.system('java -version 2>&1 | awk -F[\\\"_] \'NR==1{print $2}\'')
1.8.0
>>> os.system('java -version 2>&1 | awk -F[\\\"\.] -v OFS=. \'NR==1{print $2,$3}\'')
1.8
Answered By - fedorqui 'SO stop harming'