Technology Insights

What Package Installs more Via Yum On CentOS Linux

Typically you don’t need to install more because it is always already installed. The other night while researching something on a Windows 7 computer that had Cygwin installed we were looking to use more but it wasn’t installed. I am not sure if all default Cygwin installations don’t include more but in this case it didn’t. I typically use YUM to figure out what package provides specific applications if they are bundled with something else and not named by the command itself. Below is the output of yum whatprovides from a CentOS server when searching for the Linux package that installs more.

Technology Errors

Postfix Error: cannot update mailbox /var/mail/user for user user. error writing message: File too large

Earlier while troubleshooting an error with PHP’s mail function I noticed an error in the maillog on a CentOS server. I know I have run into this error before and previously I fixed the issue by setting a larger size limit on the Postfix mailboxes. Below is information about the Postfix error in the maillog explaining mail cannot be delivered to a specific user because the mailbox has reached the maximum size allowed as configured in the Postfix main.cf file.

Technology Insights

How to Search For Patterns In Files That Are Compressed With gzip or gunzip

It can be beneficial sometimes to search for patterns in files on a Linux server that have been compressed with gzip instead of having to uncompress each file to search through it. A good example of this if typically in log rotation you rotate the logs and compress the older log files so if you are troubleshooting an issue and need to search for an error in older log files you could use the method below to search the compressed log files to match a pattern without having to uncompress each log file.

Technology Insights

Delete All Mail Using the mail Command From the CLI of a Linux Server

Deleting mail from a Linux users local account is easy using the mail command line utility. The mail command can also be used to perform any other functions that you can think of to manage email such as replying to messages, reading messages, or just sending messages. It is very basic in nature but it does provide a great utility for simple mail tasks.

Typically most of the mail that ends up in a user account on a Linux server that I might manage comes from a cronjob or some various task that is run on a server under a users name. It is important to understand and review these messages from time to time as they may have important information in them.

Technology Insights

How to Check CPU Speed on Linux

The easiest way to check CPU speed and CPU model on Linux is to issue the below command from the CLI.

bash

  1. more /proc/cpuinfo | egrep 'model name|cpu MHz'

This will return results like the below that will list CPU model name on one line followed by CPU speed on the next line.

bash

  1. [root@server ~]# less /proc/cpuinfo | egrep 'model name|cpu MHz'
  2. model name : Dual-Core AMD Opteron(tm) Processor 2212
  3. cpu MHz : 2010.302
  4. model name : Dual-Core AMD Opteron(tm) Processor 2212
  5. cpu MHz : 2010.302
  6. model name : Dual-Core AMD Opteron(tm) Processor 2212
  7. cpu MHz : 2010.302
  8. model name : Dual-Core AMD Opteron(tm) Processor 2212
  9. cpu MHz : 2010.302