YouCompleteMe for Vim on Fedora 21 reports this error: [zma@laptop:~/.vim/bundle/YouCompleteMe]$ ./install.sh — The C compiler identification is GNU 4.9.2 — The CXX compiler identification is GNU 4.9.2 — Check for working C compiler: /usr/bin/cc — Check for working C compiler: /usr/bin/cc — works — Detecting C compiler ABI info — Detecting C compiler ABI info…
My program reports that the port is already used. How to find which program or process is listening on a certain port in Linux? You can use netstat to do this. netstat can print network connections. For example, to find which program is listing on port 9999 netstat -pln | grep 9999 You will need…
VitualBox is installed on Fedora 21 by # yum install VirtualBox The following packages are installed kmod-VirtualBox-3.18.7-200.fc21.x86_64-4.3.20-4.fc21.4.x86_64 VirtualBox-4.3.20-3.fc21.x86_64 There is the kernel modules package installed. However, when running virtualbox (after reboot), it reports: [zma@laptop:~]$ virtualbox WARNING: The vboxdrv kernel module is not loaded. Either there is no module available for the current kernel (3.18.7-200.fc21.x86_64) or…
To get files with certain string in their file names, it is quite straightforward: ls *string* However, how to do the reverse one: how to get files without certain strings in their files names on Linux? You can get a list of file names by a combination of find and xargs as follows: find ….
How to find the available packages’ versions with aptitude on Linux? With aptitude, you can use this command to show the available versions of a package: aptitude versions <package name> In the console GUI, aptitude also show the versions. You may also simulate installation of a package and see which version will be installed: aptitude…
My Linux distro is Linux Mint 17 (Ubuntu 14.04.1 LTS (Trusty Tahr)). I am using NetworkManager. The old trick does not work: $ cat /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE BY HAND — YOUR CHANGES WILL BE OVERWRITTEN nameserver 127.0.1.1 If you are using…
The logs I am processing is Hadoop log (log4j). It is in format like: 2014-09-20 21:55:11,855 INFO org.apache.hadoop.nfs.nfs3.IdUserGroup: Updated user map size: 36 2014-09-20 21:55:11,863 INFO org.apache.hadoop.nfs.nfs3.IdUserGroup: Updated group map size: 55 2014-09-20 22:10:11,907 INFO org.apache.hadoop.nfs.nfs3.IdUserGroup: Update cache now 2014-09-20 22:10:11,907 INFO org.apache.hadoop.nfs.nfs3.IdUserGroup: Not doing static UID/GID mapping because ‘/etc/nfs.map’ does not exist. Now, I…
How to find the history of updated packages by apt-get or aptitude? The history is in log files of dpkg and apt: /var/log/dpkg.log /var/log/apt/history.log /var/log/aptitude To check the recently installed packages: cat /var/log/dpkg.log | grep ” install ” To list history of recently installed packages by apt-get: cat /var/log/apt/history.log | grep ” install ” To…
How to find which files are opened by a Linux program? For example, when I run cat ~/.bashrc, how to find out which files are opened by cat? You can achieve this by using strace if the program “open” files using system calls. For example, I run as this: strace -o /tmp/st cat ./.bashrc grep…
How to debug/check network-related driver information on Linux? Several commands/tools that you may find usefull: Messages: dmesg grep NetworkManager /var/log/messages lshw: list hardware lshw -c network lsusb: list USB devices lsusb rfkill: enabling and disabling wireless devices rfkill unblock all rfkill event iwconfig: configure a wireless network interface iwconfig ifconfig: configure a network interface ifconfig
How to tell whether the shell is run in screen? For example, I run screen and it starts a bash environment. How to tell in the bash, whether it is run by screen or it is a normal bash environment? It can be identified by checking the TERM environment variable: In a bash in screen:…
For example, I want to spawn many ssh background processes in one bash script: for i in `cat ./all-hosts` do ssh $i “ifconfig | grep Link” done Simply adding a & to the ssh commands does not work. Here is the script that works: for i in `cat ./all-hosts` do ssh $i “ifconfig | grep…
I find there are too many TCP segments retransmited in a Xen virtual machine. sudo netstat -s | grep segments 537559 segments received 558908 segments send out 3533 segments retransmited 2677 bad segments received. There are 4 VMs on a host which has 4 cores. The segment retransmision rate is too high. It finally turns…
I know the routing tables on Linux is in memory after being set. However, where are the routing table entries stored on disk? I mean where are the routing table is persistently stored so that the routing table can be reloaded like the iptables (under /etc/sysconfig/iptables on Fedora/RHEL/CentOS Linuxes). If the system uses the /etc/rc.d/init.d/network…
Grub2: How to boot Fedora to an old kernel? The old kernel is a submenu under “Advanced options for Fedora”. It is not shown if I follow the instruction that # grep menuentry /boot/grub2/grub.cfg | cut -d “‘” -f2. The old kernel in grub2 is in a submenu entry in a menu. The key is…
On Linux (Fedora 17 x86-64), Chrome keeps reporting “Adobe Flash Player was blocked because it is out of date.” every time I browse a page that contains Flash. How to fix this? I did this and it turned to be working for me: Disable the libpepflashplayer in Chrome by run chrome://plugins/ in the URL bar….
I have a local svn repository. I work in the repository, e.g. compiling latex documents and building software packages, and there are many useless temporary files there. How can I clean it up by automatically clean these temporary files like the git clean -f in git? svn seems has no built-in function for this. But…
Abstract In computer systems, resources have to be balanced so that the performance will be better based on the same hardware. In Linux Kernel system, we will see some migration kernel threads running as daemons to do this kind of jobs as follows. In this article, we will discuss how Linux Kernel balances its hardware/software…
Linux may report “device is busy” when we try to umount a filesystem. This behavior is reasonable as it can help us avoid data loss by disallowing unmouting a filesystem when it is being used. But for situations when we are sure there is something wrong happened or we care not data lost such as…
Attaching a USB keyboard to a laptop is common when using a laptop because a normal keyboard may provide a more convenient typing experience. The laptop keyboard is not used in these situations. However, the laptop keyboard may still be touched by accident. In this post, we will discuss how to disable and enable the…