When I was trying to update packages on one host I’ve stuck with yum hung on update. I run strace and see: strace -p 43734 Process 43734 attached - interrupt to quit futex(0x807c938, FUTEX_WAIT, 1, NULL <unfinished ...> Process 43734 detached It looks like yum database was corrupted, to repair this run: rm -f /var/lib/rpm/__db* rpm --rebuilddb yum clean all yum update Instead rm on db-files you could use gzip to have backup of these files.
I’ve few Nagios checks that require root privileges but running nrpe as root user is not acceptable. I prefer to use sudo for only these few commands. Run visudo and coment out this line: #Defaults requiretty This change is crucial to get scripts working. Then add at the end of file: %nrpe ALL=(ALL) NOPASSWD: /usr/lib64/nagios/plugins/ I’ve used nrpe group, but you have to add exactly group that your nrpe process uses. ...
I need to check memory usage of memcached server so I used: echo stats | nc 127.0.0.1 11211 STAT pid 2743 STAT uptime 263 STAT time 1395438951 STAT version 1.4.13 STAT pointer_size 64 STAT rusage_user 0.482926 STAT rusage_system 2.675593 STAT curr_items 8667 STAT total_items 10742 STAT bytes 23802513 STAT curr_connections 296 STAT total_connections 399 STAT connection_structures 297 STAT cmd_flush 0 STAT cmd_get 52578 STAT cmd_set 10792 STAT get_hits 28692 STAT get_misses 23886 STAT evictions 0 STAT bytes_read 35984361 STAT bytes_written 192647437 STAT limit_maxbytes 536870912 STAT threads 2 STAT accepting_conns 1 STAT listen_disabled_num 0 STAT replication MASTER STAT repcached_qi_free 8189 STAT repcached_wdata 0 STAT repcached_wsize 1026048 END For me, bytes value was important but you could find more about all statistics here external link .
I have development server with postfix - I wanted to allow outbound traffic to one domain but cut off all the rest. I definitely do not want that test mail or any debug info goes to service users. I have to add something like that to /etc/postfix/transport: allowed.domain.com : * discard: Then run: postmap /etc/postfix/transport At end, add these to /etc/postfix/main.cf: transport_maps = hash:/etc/postfix/transport Reload postfix: postfix reload Test if it works: ...
In recent Ansible update to 1.5 version there is really nice feature ssh pipelining. This option is serious alternative to accelerated mode. Just add to you config file (ex. ~/.ansible.cfg): [ssh_connection] pipelining=True Now run any playbook - you will see the difference 😄 Source (and extended info about): http://blog.ansibleworks.com/2014/01/15/ssh-connection-upgrades-coming-in-ansible-1-5/ external link
I had quite simple task - compare two lists of hosts and check if hosts from first one are also on the second one. I started with diff: diff -u biglist.txt hosts_to_check.txt | grep -E "^\+" It was fine but output needs some filtering to get what I want. I’ve found another example with grep: grep -Fxv -f biglist.txt hosts_to_check.txt | sort -n This will search for all lines in hosts_to_check.txt which don’t match any line in biglist.txt. So after this I’ve got list of hosts that I have to check. That’s exactly what I need 😄
After reading some good opinions about MariaDB I wanted to give it a try. Upgrade looks quite straight forward but I found some issues a little tricky. Installation Add repo and key: cat > /etc/apt/sources.list <<SRC deb http://mirrors.supportex.net/mariadb/repo/5.5/debian wheezy main deb-src http://mirrors.supportex.net/mariadb/repo/5.5/debian wheezy main SRC (find more repositories here external link ) Now install MariaDB: sudo apt-get update sudo apt-get install mariadb-server It could be better to install mariadb-server-5.5 and mariadb-client-5.5 package instead, because of this error external link . ...
I was thinking about allowing access to my website using SPDY protocol for better performance and security (and for fun of course 😃 ). But SPDY have one disadvantage - you need SSL certificate signed by known authority that will verfiy in common browsers. So you can’t use self signed certificates because everyone will see a warning entering your site. Certs are quite expensive so I started searching for free one and to my surprise I found such! ...
I love Shotwell external link for it’s simplicity and easy export to Piwigo external link . After Christmas I added new photos to my library but after that I made some modifications to them (red eye reduction, etc…). Because Shotwell generate thumbnails only on import, all my modifications were not visible on preview. ...
Some time ago I’ve show how to precompress js and css file with gzip to be available for Nginx’s mod_gzip. In default configuration Apache don’t have such module but similar functionality could be achieved with few custom rewirtes. Basically we will start with these rewrites to serve gzipped CSS/JS files if they exist and the client accepts gzip compression: RewriteEngine on RewriteCond %{HTTP:Accept-encoding} gzip RewriteCond %{REQUEST_FILENAME}\.gz -s RewriteRule ^(.*)\.(js|css)$ $1\.$2\.gz [QSA] Then we need to setup proper content types for such compressed files - I know how to do this in two ways: ...