I am new to using bash. Now I am about to read a value, but the output of the console is too long and I just want to shorten it to the specific value.

netstat -m

24270/3315/27585 mbufs in use (current/cache/total)
4142/1724/5866/1000000 mbuf clusters in use (current/cache/total/max)
40/1478 mbuf clusters out of packet secondary zone in use (current/cache)
0/145/145/524288 4k (page size) jumbo clusters in use (current/cache/total/max)
0/0/0/524288 9k jumbo clusters in use (current/cache/total/max)
0/0/0/83968 16k jumbo clusters in use (current/cache/total/max)
...

Now I want to get to the 5866 in the second line and wrap it in a variable. Currently my script looks like this:

mbuf_stat=$(netstat -m)
mbuf=$mbuf_stat
mbuf=${mbuf#*)}
mbuf=${mbuf#*/}
mbuf=${mbuf#*/}
mbuf=${mbuf%%/*}
echo "$mbuf"

Is there an easier way to do this? It seems pretty complicated to me. Unfortunately, I have not found a simpler way yet.

CodePudding user response：

Use awk for this:

mbuf=$(netstat -m | awk -F'/' 'NR == 2 { print $3; exit }')

-F'/' makes / the field separator. NR == 2 matches the second line of the file. print $3 prints the third field, which contains 5866, then exit exits the script.

CodePudding user response：

What about this:

mbuf=$(netstat -m | grep "mbuf clusters in use" | awk -F/ '{print $3}')

The difference with the answer from Barmar is that I'm looking for the line, containing "mbuf clusters in use" instead of assuming it's the second one.

CodePudding user response：

$ netstat -m | awk -F/ '/mbuf clusters in use/{print $3}' 
5866

CodePudding user response：

mbuf=$( netstat -m | 
        
gawk '$_=$--NF' RS='^$' FS='/[^/] mbuf[^/]*clusters in use.*$|[/\n] |$' )

or

mawk -F/ '$!NF=$((NF*=/mbuf[^/]*clusters in use/)^_ NR)'

5866