'If' statement breaking his own rule or I'm doing so

Question

Explanation: I'm playing a little bit with a script this one helps notifying to user about SSL certificate expiration. If certificate has less than 30 days to expires, this will notify to user, if isn't do nothing.

But for some weird reason validating with a greater constant, even the emails is sending, and this should not happening.

This is the code:

#!/bin/ksh
    legend="The next certificate almost expires.\n URL: url.com "
    count=30
    daysleft=$(./ssl-cert-check -d /etc/ssl/certs/cert.cer | awk '{print $6}' | tail -n 1);
    #daysleft=50 #Constant to do some test
    sendnot=$(echo $legend | mail -s "url.com SSL cert Expiration" [email protected] < <(./ssl-cert-check -d /etc/ssl/certs/cert.cer))
    if [[ $daysleft -lt $count ]];
    then
    echo "Sending note"
    echo $sendnot
    else
    echo "Doing nothing..."
    fi

Doing test with daysleft constant, the statement it works; but even this anyway is sending the notes to the user.

Edit: The output of:

./ssl-cert-check -d /etc/ssl/certs/cert.cer | awk '{print $6}' | tail -n 1

is 9

Any Questions or comments I will be ready to attending. Regards!!

Answer 1

This line:

sendnot=$(echo ... | mail ... < <(./ssl-cert-check ...))

runs the commands echo, mail and ./ssl-cert-check right then and there, and captures the output of the whole lot, i.e. the output of mail, and assigns it in the variable sendnot. That's why you get the email sent regardless of the if-statement. Also, mail probably doesn't output much here, so using the command substitution seems needless.

If you want to just store a command for further use, make it a function.

send_notice() {
    local subject=$1
    echo "some message" | mail -s "$subject"
}
...
if whatever...; then
    send_notice "subject line..."
fi

($1 would be the first argument to the function.)

Also, there's another problem with that command: you're using both a pipe and an input redirection to mail. You can't connect two different things to the standard input of a command, so only one applies. With multiple redirections, it would be the last one that stays in effect; with a pipe and a redirection, it's the redirection.

So your command there is practically equal to:

mail -s ... < <(./ssl-cert-check ...)

i.e. the echo doesn't really do anything.

If you want to concatenate the outputs of the two commands, you have to do something like this:

(echo "some message"; ./ssl-cert-check ...) | mail ...