Had a surprising event on C 6.5.
Exim was the only MTA installed. It was partially configured (with ACL, Router, Transport) and definitely not running.
I was remotely testing a web page. A web page error condition invoked the embedded PHP mail() command.
To my astonishment something in Centos woke-up Exim. Exim sent the email and then became inactive again. The Exim logs does not show any start-up lines, just
1. input from Apache. 2. output to remote server. 3. 'completed'.
Hours later Logwatch, not yet customised, also caused inactive Exim to send an email (which got rejected by Exim because it was to local user 0).
What causes Centos to temporarily activate in-active (meaning non-running) Exim ?
Thanks,
Paul. England EU.
I was remotely testing a web page. A web page error condition invoked the embedded PHP mail() command.
To my astonishment something in Centos woke-up Exim. Exim sent the email and then became inactive again. The Exim logs does not show any start-up lines, just
- input from Apache.
- output to remote server.
- 'completed'.
Hours later Logwatch, not yet customised, also caused inactive Exim to send an email (which got rejected by Exim because it was to local user 0).
What causes Centos to temporarily activate in-active (meaning non-running) Exim ?
You don't really need an active smtp daemon to send email or deliver it locally. $ cat /etc/php.ini | grep sendmail
On Mon, 2014-09-29 at 00:03 +0400, Александр Кириллов wrote:
You don't really need an active smtp daemon to send email or deliver it locally. $ cat /etc/php.ini | grep sendmail
"Package(s) sendmail available, but not installed."
It was Exim because the email headers said very clearly it was Exim.
On Mon, Sep 29, 2014 at 2:05 PM, Always Learning centos@u62.u22.net wrote:
On Mon, 2014-09-29 at 00:03 +0400, Александр Кириллов wrote:
You don't really need an active smtp daemon to send email or deliver it locally. $ cat /etc/php.ini | grep sendmail
"Package(s) sendmail available, but not installed."
It was Exim because the email headers said very clearly it was Exim.
sendmail is a link to exim on most exim systems (like mine, though mine is
Ubuntu).
cliffp@ubuntu:~$ which sendmail /usr/sbin/sendmail cliffp@ubuntu:~$ file `which sendmail` /usr/sbin/sendmail: symbolic link to `exim4'
Cheers,
Cliff
On Mon, 2014-09-29 at 17:04 +1300, Cliff Pratt wrote:
sendmail is a link to exim on most exim systems (like mine, though mine is
Ubuntu).
cliffp@ubuntu:~$ which sendmail /usr/sbin/sendmail cliffp@ubuntu:~$ file `which sendmail` /usr/sbin/sendmail: symbolic link to `exim4'
C 5.10 & C 6.5
file `which sendmail`
/usr/sbin/sendmail: symbolic link to `/etc/alternatives/mta'
strings /etc/alternatives/mta |grep exim
produces Exim lines. No results for Postfix or for Sendmail.
Thanks. I learned something new today.
Paul. England, EU.
On Mon, Sep 29, 2014 at 8:40 AM, Always Learning centos@u62.u22.net wrote:
sendmail is a link to exim on most exim systems (like mine, though mine is
Ubuntu).
cliffp@ubuntu:~$ which sendmail /usr/sbin/sendmail cliffp@ubuntu:~$ file `which sendmail` /usr/sbin/sendmail: symbolic link to `exim4'
C 5.10 & C 6.5
file `which sendmail`
/usr/sbin/sendmail: symbolic link to `/etc/alternatives/mta'
strings /etc/alternatives/mta |grep exim
produces Exim lines. No results for Postfix or for Sendmail.
Thanks. I learned something new today.
Not exactly... Applications that pipe to the sendmail command line program to send messages go back to the dawn of email. MTAs that replace the 'real' sendmail pretty much have to provide that functionality.
On Mon, 2014-09-29 at 10:49 -0500, Les Mikesell wrote:
On Mon, Sep 29, 2014 at 8:40 AM, Always Learning centos@u62.u22.net wrote:
sendmail is a link to exim on most exim systems (like mine, though mine is
Ubuntu).
cliffp@ubuntu:~$ which sendmail /usr/sbin/sendmail cliffp@ubuntu:~$ file `which sendmail` /usr/sbin/sendmail: symbolic link to `exim4'
C 5.10 & C 6.5
file `which sendmail`
/usr/sbin/sendmail: symbolic link to `/etc/alternatives/mta'
strings /etc/alternatives/mta |grep exim
produces Exim lines. No results for Postfix or for Sendmail.
Thanks. I learned something new today.
Not exactly... Applications that pipe to the sendmail command line program to send messages go back to the dawn of email. MTAs that replace the 'real' sendmail pretty much have to provide that functionality.
Yes I did learn something new.
I started to use Linux, Centos, in desperation to rid myself of Windoze. I plunged-in, never learned the theory because of inadequate time. Hence I am Always Learning and never falling to be impressed, continuously delighted to be rid of M$ and wishing I have ventured into Linux 10+ years earlier than I did.
Always Learning wrote:
On Mon, 2014-09-29 at 10:49 -0500, Les Mikesell wrote:
On Mon, Sep 29, 2014 at 8:40 AM, Always Learning centos@u62.u22.net wrote:
<snip>
Thanks. I learned something new today.
Not exactly... Applications that pipe to the sendmail command line program to send messages go back to the dawn of email. MTAs that replace the 'real' sendmail pretty much have to provide that functionality.
Yes I did learn something new.
I started to use Linux, Centos, in desperation to rid myself of Windoze. I plunged-in, never learned the theory because of inadequate time. Hence I am Always Learning and never falling to be impressed, continuously delighted to be rid of M$ and wishing I have ventured into Linux 10+ years earlier than I did.
A *very* strong recommendation: find a copy of Frisch's Essential Systems Administration, published by O'Reilly. Some of it's out of date, some more Unix than Linux... but read chapter 2, "The Unix Way". A *lot* will be a lot clearer.
mark "been shoving this at people for > 15 years"
On Sep 29, 2014, at 14:44, m.roth@5-cent.us wrote:
Always Learning wrote:
On Mon, 2014-09-29 at 10:49 -0500, Les Mikesell wrote:
On Mon, Sep 29, 2014 at 8:40 AM, Always Learning centos@u62.u22.net wrote:
<snip> >>> Thanks. I learned something new today. >> >> Not exactly... Applications that pipe to the sendmail command line >> program to send messages go back to the dawn of email. MTAs that >> replace the 'real' sendmail pretty much have to provide that >> functionality. > > Yes I did learn something new. > > I started to use Linux, Centos, in desperation to rid myself of Windoze. > I plunged-in, never learned the theory because of inadequate time. Hence > I am Always Learning and never falling to be impressed, continuously > delighted to be rid of M$ and wishing I have ventured into Linux 10+ > years earlier than I did.
A *very* strong recommendation: find a copy of Frisch's Essential Systems Administration, published by O'Reilly. Some of it's out of date, some more Unix than Linux... but read chapter 2, "The Unix Way". A *lot* will be a lot clearer.
mark "been shoving this at people for > 15 years
I second and third that recommendation. A great exercise is to use that book as a foundation, and to realize that the “what to do” has not changed that much, but the “how to do it” changes hourly. Each year as I cull my tech library, the O’Reilly books are almost never passed on to the local library. I can count on them to show the best practices / philosophies / approaches, and then I research what has changed since it was published by directed web site searching and man paging.
Don
On Mon, Sep 29, 2014 at 2:10 PM, Don O'Hara don.ohara@gmail.com wrote:
I second and third that recommendation. A great exercise is to use that book as a foundation, and to realize that the “what to do” has not changed that much, but the “how to do it” changes hourly.
Sigh... I'm rarely convinced that "how you _should_ do something" should change just because some programmer that didn't understand the old, working way wrote something new and buggy.
On Mon, 2014-09-29 at 14:44 -0400, m.roth@5-cent.us wrote:
Always Learning wrote:
On Mon, 2014-09-29 at 10:49 -0500, Les Mikesell wrote:
On Mon, Sep 29, 2014 at 8:40 AM, Always Learning centos@u62.u22.net wrote:
<snip> >> > Thanks. I learned something new today. >> >> Not exactly... Applications that pipe to the sendmail command line >> program to send messages go back to the dawn of email. MTAs that >> replace the 'real' sendmail pretty much have to provide that >> functionality. > > Yes I did learn something new. > > I started to use Linux, Centos, in desperation to rid myself of Windoze. > I plunged-in, never learned the theory because of inadequate time. Hence > I am Always Learning and never falling to be impressed, continuously > delighted to be rid of M$ and wishing I have ventured into Linux 10+ > years earlier than I did.
A *very* strong recommendation: find a copy of Frisch's Essential Systems Administration, published by O'Reilly. Some of it's out of date, some more Unix than Linux... but read chapter 2, "The Unix Way". A *lot* will be a lot clearer.
Its the time required to read non-essential items. Too many important demands on my time and too much work to do.
Might try at Christmas if fewer demands on my time and energy.
Thanks for the tip.
Always Learning wrote:
On Mon, 2014-09-29 at 14:44 -0400, m.roth@5-cent.us wrote:
Always Learning wrote:
On Mon, 2014-09-29 at 10:49 -0500, Les Mikesell wrote:
On Mon, Sep 29, 2014 at 8:40 AM, Always Learning centos@u62.u22.net wrote:
<snip> >> > Thanks. I learned something new today. >> >> Not exactly... Applications that pipe to the sendmail command line >> program to send messages go back to the dawn of email. MTAs that >> replace the 'real' sendmail pretty much have to provide that >> functionality. > > Yes I did learn something new. > > I started to use Linux, Centos, in desperation to rid myself of > Windoze. I plunged-in, never learned the theory because of inadequate
time.
Hence I am Always Learning and never falling to be impressed,
continuously
delighted to be rid of M$ and wishing I have ventured into Linux 10+ years earlier than I did.
A *very* strong recommendation: find a copy of Frisch's Essential Systems Administration, published by O'Reilly. Some of it's out of
date, some
more Unix than Linux... but read chapter 2, "The Unix Way". A *lot*
will be a
lot clearer.
Its the time required to read non-essential items. Too many important demands on my time and too much work to do.
I'm just pushing one chapter at you.
I got into systems administration back in the mid-nineties. Two weeks after I was hired for a startup division of a huge telecom (a Baby Bell), I was asked if I wanted to pick up systems admin from one of the consultants, who'd be rolling off. I said, sure....
Almost a year later, when the division had grown from 4 groups to 27(!), and they brought in the corporate sysadmins, I got friendly with them, and kept doing most of the work on the server our teams under our director used. They told me of all the servers, *two* (count them) looked normal (as opposed to everyone having the root password, files and directories all over the place, etc, etc), and mine was one... and that was because I'd been sleeping with Frisch's book, as well as my ...late... wife.
Might try at Christmas if fewer demands on my time and energy.
*Make* the time. It'll save your bacon.
mark
Always Learning wrote:
On Mon, 2014-09-29 at 15:27 -0400, m.roth@5-cent.us wrote:
*Make* the time. It'll save your bacon.
I will look for the book. An egg and crispy bacon sandwich would be nice.
Yup - British bacon may well be better than American (even when you can get American bacon that's not 75% or more fat)....
mark
On Mon, Sep 29, 2014 at 1:41 PM, Always Learning centos@u62.u22.net wrote:
Thanks. I learned something new today.
Not exactly... Applications that pipe to the sendmail command line program to send messages go back to the dawn of email. MTAs that replace the 'real' sendmail pretty much have to provide that functionality.
Yes I did learn something new.
Just new to you...
I started to use Linux, Centos, in desperation to rid myself of Windoze. I plunged-in, never learned the theory because of inadequate time. Hence I am Always Learning and never falling to be impressed, continuously delighted to be rid of M$ and wishing I have ventured into Linux 10+ years earlier than I did.
If you really want to appreciate the concepts, you should find a unix manual from the days before X was included. Back then there were 5 sections where 1 covered the command line programs, 2 covered system calls, 3 the standard C library, etc. It was small enough that you could read and mostly memorize it, especially section 1, in a few days. The thing to appreciate is that 30+ years later, even in cloned versions, those things were designed well enough that pretty much everything in there still continues to work.
On Mon, 2014-09-29 at 14:03 -0500, Les Mikesell wrote:
On Mon, Sep 29, 2014 at 1:41 PM, Always Learning centos@u62.u22.net wrote:
Thanks. I learned something new today.
Not exactly... Applications that pipe to the sendmail command line program to send messages go back to the dawn of email. MTAs that replace the 'real' sendmail pretty much have to provide that functionality.
Yes I did learn something new.
Just new to you...
No. Not only to me but also new to others who, like me, never knew. Learning is a continuous process :-)
If you really want to appreciate the concepts, you should find a unix manual from the days before X was included. Back then there were 5 sections where 1 covered the command line programs, 2 covered system calls, 3 the standard C library, etc. It was small enough that you could read and mostly memorize it, especially section 1, in a few days. The thing to appreciate is that 30+ years later, even in cloned versions, those things were designed well enough that pretty much everything in there still continues to work.
Design is so important. Get it really right the first time and vast amounts of time and effort are saved. If I ever encounter a Unix book or manual, I'll certainly keep it to read.
Thank you.
Paul. England, EU.
On Mon, Sep 29, 2014 at 2:23 PM, Always Learning centos@u62.u22.net wrote:
If you really want to appreciate the concepts, you should find a unix manual from the days before X was included. Back then there were 5 sections where 1 covered the command line programs, 2 covered system calls, 3 the standard C library, etc. It was small enough that you could read and mostly memorize it, especially section 1, in a few days. The thing to appreciate is that 30+ years later, even in cloned versions, those things were designed well enough that pretty much everything in there still continues to work.
Design is so important. Get it really right the first time and vast amounts of time and effort are saved. If I ever encounter a Unix book or manual, I'll certainly keep it to read.
There is plenty of documentation around now, but it is much, much harder to sort out the core tools from the cruft and specialty stuff now. If you understand what the fork() system call does, most of the rest of what unix-like systems do will generally make sense.
The daemon only handles incoming mail, or in other words waits for incoming connections from other mail servers. Outgoing mail is sent on demand, or in other words a connection is made to a mail server or relay as and when required.
Cheers,
Cliff
On Mon, Sep 29, 2014 at 8:01 AM, Always Learning centos@u62.u22.net wrote:
Had a surprising event on C 6.5.
Exim was the only MTA installed. It was partially configured (with ACL, Router, Transport) and definitely not running.
I was remotely testing a web page. A web page error condition invoked the embedded PHP mail() command.
To my astonishment something in Centos woke-up Exim. Exim sent the email and then became inactive again. The Exim logs does not show any start-up lines, just
- input from Apache.
- output to remote server.
- 'completed'.
Hours later Logwatch, not yet customised, also caused inactive Exim to send an email (which got rejected by Exim because it was to local user 0).
What causes Centos to temporarily activate in-active (meaning non-running) Exim ?
Thanks,
Paul. England EU.
CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
On Sun, Sep 28, 2014 at 2:01 PM, Always Learning centos@u62.u22.net wrote:
Had a surprising event on C 6.5.
Exim was the only MTA installed. It was partially configured (with ACL, Router, Transport) and definitely not running.
I was remotely testing a web page. A web page error condition invoked the embedded PHP mail() command.
To my astonishment something in Centos woke-up Exim. Exim sent the email and then became inactive again. The Exim logs does not show any start-up lines, just
- input from Apache.
- output to remote server.
- 'completed'.
Hours later Logwatch, not yet customised, also caused inactive Exim to send an email (which got rejected by Exim because it was to local user 0).
What causes Centos to temporarily activate in-active (meaning non-running) Exim ?
Applications often send mail by piping to the command 'sendmail' which is enough of a standard that other MTAs normally offer a compatible command. With 'real' sendmail you can configure it to either deliver in the current process or to queue for subsequent delivery by the daemon. Not sure how the others handle it, but yours apparently completes the delivery.
On Sun, 2014-09-28 at 19:27 -0500, Les Mikesell wrote:
Applications often send mail by piping to the command 'sendmail' which is enough of a standard that other MTAs normally offer a compatible command. With 'real' sendmail you can configure it to either deliver in the current process or to queue for subsequent delivery by the daemon. Not sure how the others handle it, but yours apparently completes the delivery.
Sendmail is not present on the server. Exim is the only MTA. Exim awoke, forwarded the email then became inactive (not running) again.
I was curious how a non-running Exim can be run, solely to forward mail, then returned to its inactive state. I assume some system software identified the PHP outgoing email, and launched the only MTA installed (Exim) just to handle the outgoing email.
On Mon, Sep 29, 2014 at 02:52:45AM +0100, Always Learning wrote:
Sendmail is not present on the server. Exim is the only MTA. Exim awoke, forwarded the email then became inactive (not running) again.
He didn't say sendmail the package was present; he said sendmail the command.
rpm -qvl exim | grep sendmail
Those targets are used by the alternatives system and provide backwards compatibility with the _industry standard_ of /usr/sbin/sendmail and /usr/lib/sendmail, which are expected interfaces.
I was curious how a non-running Exim can be run, solely to forward mail, then returned to its inactive state. I assume some system software identified the PHP outgoing email, and launched the only MTA installed (Exim) just to handle the outgoing email.
exim sends mail by default; nothing needs to be running to do so.
John
-
Always Learning -
Cliff Pratt -
Don O'Hara -
John R. Dennison -
Les Mikesell -
m.roth＠5-cent.us -
Александр Кириллов