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probackup-nl

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From: Delft

Registered: 2017-11-15

Posts: 93

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PAM pam_exec.so: echo statement causes "conversation failed" in journa

Journalctl list loads of conversation failed lines:

Feb 12 14:53:19 influxPi4B sshd[4231]: pam_exec(sshd:session): conversation failed
Feb 12 14:53:19 influxPi4B sshd[4231]: pam_exec(sshd:session): conversation failed
Feb 12 14:53:19 influxPi4B sshd[4231]: pam_exec(sshd:session): conversation failed
Feb 12 14:53:19 influxPi4B sshd[4231]: pam_exec(sshd:session): conversation failed
Feb 12 14:53:19 influxPi4B sshd[4231]: pam_exec(sshd:session): conversation failed
Feb 12 14:53:19 influxPi4B sshd[4231]: pam_exec(sshd:session): conversation failed
Feb 12 14:53:19 influxPi4B sshd[4231]: pam_exec(sshd:session): conversation failed
Feb 12 14:53:19 influxPi4B sshd[4231]: pam_exec(sshd:session): conversation failed
Feb 12 14:53:19 influxPi4B sshd[4231]: pam_exec(sshd:session): conversation failed
Feb 12 14:53:19 influxPi4B sshd[4231]: pam_exec(sshd:session): conversation failed
Feb 12 14:53:19 influxPi4B sshd[4231]: pam_exec(sshd:session): conversation failed

As in a similar (5 year old) case https://bbs.archlinux.org/viewtopic.php?id=208685 these event messages  to the pam_exec.so module. When I comment the pam_exec.so line, I don't have theses messages anymore.

# tail /etc/pam.d/system-login
password   include    system-auth

session    optional   pam_loginuid.so
session    optional   pam_keyinit.so       force revoke
session    include    system-auth
session    optional   pam_motd.so          motd=/etc/motd
session    optional   pam_mail.so          dir=/var/spool/mail standard quiet
-session   optional   pam_systemd.so
session    required   pam_env.so           user_readenv=1
session    optional   pam_exec.so          stdout /usr/bin/motd.sh

Moving the pam_exec motd script call to "/etc/pam.d/system-auth" also results in "conversation failed" messages. Now by systemd process, and not sshd process.

Update: 19 lines in journal
There are 19 duplicate lines in journal, on every login. There are also 19 echo commands in the script, most of them like:

echo -e "xyz $var etcetera"

When I comment some echo lines, the number of "conversation failed" lines reduce. After removing the comments for the echo commands, the amount of "conversation failed" lines increase.

Any idea how to fix this error and/or what is wrong with echo?
Could the echo statements be the problem?
Are there special requirements for scripts that get executed via pam_exec?

Last edited by probackup-nl (2021-02-12 15:15:39)