shell script get the previous column based on following column value

Question

Hi I'm currently writing shell script and need to get the value from a column when the next column matches a value. An example of the output to be search is below.

con1{649}:  AES_CBC_256/HMAC_SHA2_256_128/MODP_2048, 306081 bytes_i, 444452 bytes_o, rekeying in 6 minutes

So in the above output I'm look to extract the "306081" but as the column can move I want to grab the column befores value of "bytes_i"

I've tried the following but it fails to return as value ipsec statusall | grep con1{ | awk -v b="bytes_i" '{for (i=1;i\<=NF;i++) { if ($i == b) { print i } }}

I was thinking if I could get the colume number of bytes_i I could subtrack 1 and then use awk to grab that column value but I'm open to suguestions.

`ipsec statusall | sed '/con1{/!d;/ bytes_i.*/!d;s///;s/.* //'` — jhnc, Mar 23 '22 at 22:52
That's a separate problem; `set +H` and try again. https://stackoverflow.com/questions/11816122/echo-fails-event-not-found — tripleee, Mar 27 '22 at 06:40

score 0 · Answer 1 · answered Mar 24 '22 at 17:41

I'm sure there is probably a more optimal way to do this but I've managed to solve it with the following shell script. The following function in my code with $1 being the connection to look for and $2 is the value I was looking for to get the number before it.

ipsec_get_bytes()
{
  for ipsec in $(ipsec statusall | grep $1\{ | grep bytes_ | tr -su ' ' '\n' | tail -n +2)
  do
    if [ "$ipsec" == "$2" ] || [ "$ipsec" == "$2," ]; then
      echo $ipsec_prev
      break
    else
      ipsec_prev=$ipsec
    fi
  done

}

score 0 · Answer 2 · answered Mar 27 '22 at 05:30

0

You could use sed with back-references:

ipsec statusall | sed -n 's/\(.*\) \([0-9]*\) \(bytes_i.*\)/\2/p'

This will return the numeric string that immediately precedes bytes_i.

answered Mar 27 '22 at 05:30

fuzzydrawrings

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shell script get the previous column based on following column value

2 Answers2