Posts Tagged ‘xargs’

Unfreeze stucked “freezed” messages from Exim Mail server queue

Friday, June 16th, 2023


Messages are frozen when the mail server has determined it cannot do anything to deliver the message. (they can also be manually frozen).

Exim has option to set how long frozen messages are kept on the system.

On a Debian/Ubuntu based install the /etc/exim4/conf.d/main/02_exim4-config_options file has the option timeout_frozen_after = 7d. Which means messages frozen for 7 days will get expunged.

Frozen messages really shouldn't be a problem on most systems. They are often just spam messages that can't get properly delivered.

If you have to deal with freezed mails from the exim mail server, unlike postfix, where there is no "freeze" scheme but the messages just stuck in the queue and you might want to simply ask the mail server to resend failed to deliver messages once again through a simple:

# postqueue -f

With exim to ask the server to resend the freeze-d states messages there is another aproach:

It is for this reason that I am writing this post to share how you can ask the exim to resend the "frozen" messages, as on exim there is no so much straight forward way.

To find out what letters are stored in the exim queue run

# exim -bp

To unfreeze the messages a simple while loop can be written, which lists all frozen state messages and unfreezes these letters one by one in a cycle:

# exim -bp | grep -i frozen | awk '{print $3}' | while read LINE; do exim -Mt $LINE; done

Another approach to unfreeze the frozen multitude of messages which should be a bit quicker if you have to do it for a very large amount of frozen states mails is to use xargs command:

# mailq | grep frozen | awk '{print $3}' | xargs exim -v -M

Since we on exim topic in this article, for starters with Exim, here is few other useful exim queue commands, that might be beneficial if you have to deal with EXIM SMTP.

Attempting to send a mail with a specified ID

# /usr/sbin/exim -M email-id

Forcefully run another queue to execute

# /usr/sbin/exim -qf

We see the logs related to letter

# /usr/sbin/exim -Mvl messageID

To see the body of the letter

# /usr/sbin/exim -Mvb messageID

To see the beginning (header) of the letter only

# /usr/sbin/exim -Mvh messageID

Deletes the mail without sending any error messages

# /usr/sbin/exim -Mrm messageID

Shows the number of letters in the queue

# /usr/sbin/exim -bpr | grep "<" | wc -l

Shows the number of frozen mails in the queue

# /usr/sbin/exim -bpr | grep frozen | wc -l

Deletes all frozen letters

# /usr/sbin/exim -bpr | grep frozen | awk {'print $3'} | xargs exim -Mrm

To remove a message from the Exim queue

# exim -Mrm {message-id}

Remove all messages from the Exim queue

# exim -bp | awk '/^ *[0-9]+[mhd]/{print "exim -Mrm " $3}' | bash

Another way to do it:

# exim -bp | exiqgrep -i | xargs exim -Mrm

Fastest solution to delete all emails in exim queue (for less than 5 seconds) is

# cd /var/spool
# mv exim exim.old
# mkdir -p exim/input
# mkdir -p exim/msglog
# mkdir -p exim/db
# chown -R mail:mail exim
# /sbin/service exim restart

or if you have AV / AntiSpam integrated to mail server:

# cd /var/spool
# mv exim exim.old
# mkdir -p exim/db
# mkdir -p exim/input
# mkdir -p exim/msglog
# mkdir -p exim/scan
# chown -R mail:mail exim
# /sbin/service exim restart

Deletes the entire exim queue

# /usr/sbin/exim -qff

Linux: How to change recursively directory permissions to executable (+x) flag

Monday, September 2nd, 2013

change recursively permissions of directories and subdirectories Linux and Unix with find command
I had to copy large directory from one Linux server to windows host via SFTP proto (with WinSCP). However some of directories to be copied lacked executable flag, thus WinSCP failed to list and copy them.

Therefore I needed way to set recursively, all sub-directories under directory /mirror (located on Linux server) to +x executable flag.

There are two ways to do that one is directly through find cmd, second by using find with xargs
Here is how to do it with find:

# find /mirror -type d -exec chmod 755 {} + Same done with find + xargs:

# find /path/to/base/dir -type d -print0 | xargs -0 chmod 755
To change permissions only to all files under /mirror server directory with find

# find /path/to/base/dir -type f -exec chmod 644 {} +

Same done with find + xargs:
# find /path/to/base/dir -type f -print0 | xargs -0 chmod 644

Also, tiny shell script that recursively changes directories permissions ( is here

find text strings recursively in Linux and UNIX – find grep in sub-directories command examples

Tuesday, May 13th, 2014

GNU Grep
is equipped with a special option "-r" to grep recursively. Looking for string in a file in a sub-directories tree with the -r option is a piece of cake. You just do:

grep -r 'string' /directory/

or if you want to search recursively non-case sensitive for text

grep -ri 'string' .

Another classic GNU grep use (I use almost daily) is whether you want to match all files containing (case insensitive) string  among all files:

grep -rli 'string' directory-name

Now if you want to grep whether a string is contained in a file or group of files in directory recursively on some other UNIX like HP-UX or Sun OS / Solaris where there is no GNU grep installed by default here is how to it:

find /directory -exec grep 'searched string' {} dev/null ;

Note that this approach to look for files containing string on UNIX is very slowThus on not too archaic UNIX systems for some better search performance it is better to use xargs;

find . | xargs grep searched-string

A small note to open here is by using xargs there might be weird results when run on filesystems with filenames starting with "-".

Thus comes the classical (ultimate) way to grep for files containing string with find + grep, e.g.

find / -exec grep grepped-string {} dev/null ;

Another way to search a string recursively in files is by using UNIX OS '*' (star) expression:

grep pattern * */* */*/* 2>/dev/null

Talking about recursive directory text search in UNIX, should mention  another good GNU GREP alternative ACK – check it on 🙂 . Ack is perfect for programmers who have to dig through large directory trees of code for certain variables, functions, objects etc.