How to do a logical OR operation in shell scripting

Question

I am trying to do a simple condition check, but it doesn\'t seem to work.

If $# is equal to 0 or is greater than 1 then say he

Answer 1

And in Bash

 line1=`tail -3 /opt/Scripts/wowzaDataSync.log | grep "AmazonHttpClient" | head -1`
 vpid=`ps -ef|  grep wowzaDataSync | grep -v grep  | awk '{print $2}'`
 echo "-------->"${line1}
    if [ -z $line1 ] && [ ! -z $vpid ]
    then
            echo `date --date "NOW" +%Y-%m-%d` `date --date "NOW" +%H:%M:%S` :: 
            "Process Is Working Fine"
    else
            echo `date --date "NOW" +%Y-%m-%d` `date --date "NOW" +%H:%M:%S` :: 
            "Prcess Hanging Due To Exception With PID :"${pid}
   fi

OR in Bash

line1=`tail -3 /opt/Scripts/wowzaDataSync.log | grep "AmazonHttpClient" | head -1`
vpid=`ps -ef|  grep wowzaDataSync | grep -v grep  | awk '{print $2}'`
echo "-------->"${line1}
   if [ -z $line1 ] || [ ! -z $vpid ]
    then
            echo `date --date "NOW" +%Y-%m-%d` `date --date "NOW" +%H:%M:%S` :: 
            "Process Is Working Fine"
    else
            echo `date --date "NOW" +%Y-%m-%d` `date --date "NOW" +%H:%M:%S` :: 
            "Prcess Hanging Due To Exception With PID :"${pid}
  fi

Answer 2

From Bash Reference Manual → 3.4.2 Special Parameters

#
($#) Expands to the number of positional parameters in decimal.

Therefore, $# will always be either 0 or a bigger integer.

So if you want to do something whenever $# is either 0 or bigger than 1, you just have to check if $# is or is not 1:

[ $# -eq 1 ] && echo "1 positional param" || echo "0 or more than 1"

This uses the syntax:

[ condition ] && {things if true} || {things if false}