I support a couple of yum repositories, and use the yum repository build instructions documented in my previous post to create my repositories. When I tried to apply the latest CentOS 5.3 updates to one of my servers last week, I noticed that I was getting a number of “Error performing checksum” errors: $ yum [...]
Most Linux distributions ship with the netconsole service, which allows kernel printk() messages to be sent to a remote destination. This feature can be useful for debugging system hangs and panics, and is handy for archiving console messages to a central location. To configure netconsole, you will need to add the IP address of a [...]
While debugging an application a few weeks back, I noticed the following error in the application log: Cannot open file : Too many open files The application runs as an unprivileged user, and upon closer inspection I noticed that the maximum number of file descriptors available to the process was 1024: $ ulimit -n 1024 [...]
One of things I love about Solaris is its ability to generate a core file when a system panics. The core files are an invaluable resource for figuring out what caused a host to panic, and are often the first thing OS vendor support organizations will request when you open a support case. Linux provides [...]
The netkit-ftp client that ships with Redhat Enterprise Linux comes with a verbose option, which will among other things instruct the client to print the number of bytes transferred after each file is successfully sent. These messages look similar to the following: 85811076 bytes sent in 1.3e+02 seconds (6.7e+02 Kbytes/s) I had several enormous files [...]
While testing out LDAP authentication on a CentOS 4.4 Linux host this week, I noticed that the “password” statements I added to /etc/pam.d/sshd weren’t taking effect: password requisite /lib/security/$ISA/pam_cracklib.so retry=3 password sufficient /lib/security/$ISA/pam_unix.so nullok use_authtok md5 shadow password sufficient /lib/security/$ISA/pam_ldap.so use_authtok password required /lib/security/$ISA/pam_deny.so After pondering the issue for a while, I eventually started to [...]
