Shortest command to calculate the sum of a column of output on Unix?

unix math shell ksh
An̲̳̳drew picture An̲̳̳drew · Nov 17, 2008 · Viewed 83.2k times · Source

I'm sure there is a quick and easy way to calculate the sum of a column of values on Unix systems (using something like awk or xargs perhaps), but writing a shell script to parse the rows line by line is the only thing that comes to mind at the moment.

For example, what's the simplest way to modify the command below to compute and display the total for the SEGSZ column (70300)?

ipcs -mb | head -6
IPC status from /dev/kmem as of Mon Nov 17 08:58:17 2008
T         ID     KEY        MODE        OWNER     GROUP      SEGSZ
Shared Memory:
m          0 0x411c322e --rw-rw-rw-      root      root        348
m          1 0x4e0c0002 --rw-rw-rw-      root      root      61760
m          2 0x412013f5 --rw-rw-rw-      root      root       8192

Answer

Johannes Schaub - litb picture Johannes Schaub - litb · Nov 17, 2008 
ipcs -mb | tail +4 | awk '{ sum += $7 } END { print sum }'

Or without tail:

ipcs -mb | awk 'NR > 3 { sum += $7 } END { print sum }'

Using awk with bc to have arbitrary long results (credits to Jouni K.):

ipcs -mb | awk 'NR > 3 { print $7 }' | paste -sd+ | bc

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