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bashopensslstdoutstderr

How to send openssl s_client -connect stdout and stderr to /dev/null?

I have following bash script that checks the existence of a given SSL client certificate in Apache.

#!/bin/bash
cert=$1
echo | openssl s_client -connect localhost:443 | grep -q $cert > /dev/null 2>&1
if [ $? -eq 0 ]; then
  echo $cert "client cert already exist"
else
  #Create a new client cert in Apache
fi

Even though I am sending stdout and stderr of openssl command to /dev/null, the command is still showing the following error to the console!

depth=3 C = OM, O = ORG, OU = For Staging, CN = ROOT CA - 1 verify error:num=19:self signed certificate in certificate chain verify return:0 /C=om/O=o/CN=MY_CERT DONE

Solution

  • The problem is that you're not actually sending openssl's stderr to /dev/null, but grep's.

    To send openssl's stderr to /dev/null you need to put the redirection into the same part of the pipe as the openssl invocation. And as you're using grep -q you don't need any I/O redirection on grep.

    This shoud do it:

    echo | openssl s_client -connect localhost:443 2>/dev/null | grep -q $cert