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After following several tutorials on setting up postfix at basic level on CentOs for my VPS, continue to get the following:

-bash-4.1# postfix start
/usr/libexec/postfix/postfix-script: line 317: cmp: command not found
postfix/postfix-script: warning: /usr/lib/sendmail and /usr/sbin/sendmail differ
postfix/postfix-script: warning: Replace one by a symbolic link to the other
postfix/postfix-script: starting the Postfix mail system

In the main.cf below are my edits:

myhostname = myservername.sub.mysite.net
mydomain = sub.mysite.net
myorigin = $myhostname
myorigin = $mydomain 
inet_interfaces = all
inet_interfaces = $myhostname
inet_interfaces = localhost
mydestination = $myhostname, localhost.$mydomain, localhost
mynetworks =,

Also removed sendmail but haven't yet set up db, just trying to get postfix to start without errors.

Is this the problem? why are two files in red? usr/sbin

share|improve this question
What's the output of which cmp? The first line suggests to me that postfix is running sanity checks which rely on it. (Strange, I've never seen an install without it.) – Ulrich Schwarz Dec 12 '12 at 7:01
the output of the command. For me, it's ~ % which cmp giving /usr/bin/cmp – Ulrich Schwarz Dec 12 '12 at 9:43
I can't find what you are talking about sorry? – freja Dec 12 '12 at 10:08
/usr/bin/which: no cmp in (/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin) – freja Dec 12 '12 at 10:09
Installed: diffutils.i686 0:2.8.1-28.el6 Complete! -bash-4.1# postfix stop postfix/postfix-script: stopping the Postfix mail system -bash-4.1# postfix start postfix/postfix-script: starting the Postfix mail system -bash-4.1# – freja Dec 12 '12 at 10:21
up vote 1 down vote accepted

You're probably lacking the diffutils package, which will provide the cmp binary that postfix needs for its sanity checks.

sudo yum install diffutils

should help you on.

share|improve this answer
thanks - see above already worked that out – freja Dec 12 '12 at 10:31
you were a few minutes too late with your answer :P – freja Dec 12 '12 at 10:31
can u tell me mistake here pls? -bash-4.1# postconf -e postfix_mydestination = localhost burra.yabbit.net postconf: fatal: missing '=' after attribute name: "postfix_mydestination" – freja Dec 12 '12 at 10:32
@freja: Sorry, I'm not a mail person at all really. – Ulrich Schwarz Dec 12 '12 at 11:23

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