How to Check if a Key Exists in a Python Dict Checking for key existence is a fundamental operation in Python to avoid KeyError. The Code if ‘key’ in my_dict: print(“Exists”) Python in 2026 In 2026, the in operator is still the most Pythonic and fastest way to check for keys. For more complex logic,…
How tinstall aria2 on Rocky Linux 9? aria2 is a great tool for downloading files from the Internet. The software package for aria2 is proved in EPEL. To install aria2, first, enable EPEL following instructions here. Then, install aria2 by # yum install aira2 Editor’s note: This article has been updated to reflect current software…
curtlftpfs is a nice tool to mount ftp to local. How to install curlftpfs on Rocky Linux 9? The software package for curlftpfs is proved in EPEL. To install curlftpfs, first, enable EPEL following instructions here. Then, install curlftpfs by # yum install curlftpfs Editor’s note: This article has been updated to reflect current software…
For my case, I need to bypass one intermediate server so that I can connect to the remote server with vnc. For example, there are two servers (s1, s2) except my local PC and I have to login to s1 so that I can login s2 from my local PC. However, now, I need to…
sshfs is a nice tool. But it seems there is no support to it in a newly installed Rocky Linux 9 Linux system: Not installed by default: # sshfs -bash: sshfs: command not found Seems not available from the repositories # yum install sshfs -y Loaded plugins: fastestmirror Repodata is over 2 weeks old. Install…
If we want to change the tick time for Linux Kernel, we need to change CONFIG_HZ parameter in Linux Kernel. Do we have other better ways to change it rather than compiling Linux Kernel. Please ignore the way to add ‘divider=10’ in grub config file because it is limited only for RH/CentOS distros. Zhiqiang, please…
My Ubuntu boots to GUI mode by default. How to make Ubuntu Linux boot to text mode? If you are using Ubuntu older than 16 such as Ubuntu 24.04 LTS: Edit /etc/default/grub Change GRUB_CMDLINE_LINUX=… to GRUB_CMDLINE_LINUX=”text”. Backup your old grub config`$ sudo cp -n /etc/default/grub /etc/default/grub.bak-date +%s ` Update grub$ sudo update-grub If you are…
Firefox on CentOS7 does not have Flash enabled by default. How to install Flash Player plugin on Rocky Linux 9? You may follow this tutorials to build a freshwrapper based flash plugin for Firefox on Rocky Linux 9. If you don’t want to build it by yourself, you may download the pre-built .so from from…
I find the rtl8192cu wireless adapter driver on Rocky Linux 9 is quite unstable. After running a while, the connection will disappear. How to make it stable? There is a bug in some hardware where the device never wakes back up. You may try disabling the power management by putting a file 8192cu-disable-power-management.conf under /etc/modprobe.d/:…
I tried to build a project while it reports: # ./autogen.sh Can’t exec “aclocal”: No such file or directory at /usr/share/autoconf/Autom4te/FileUtils.pm line 326. autoreconf: failed to run aclocal: No such file or directory How should I handle this? How to install aclocal? yum install aclocal shows: No package aclocal available. Error: Unable to find a…
Hello, I have installed Xen4Centos on Centos7, having single NIC card with bridge network and have two VMs on that. In one VM, I want to add two static IP one for webserver and one for mail server. So I have created IP alias in guest VM, it was created but it was not pinging…
For local filesystems, root usually has full access (read/write) to directories/files inside of it. But for NFS directory mounted from network, root usually has no permission to write to directories or files within the NFS directory. How to make root act similarly in an NFS directory to the behavior in local directories? The reason that…
When I tried to apply new configuration in /etc/sysctl.conf, I got following message. warning: /etc/sysctl.conf(44): invalid syntax, continuing… Sounds like your changed /etc/sysctl.conf has problem. You may post the content of your /etc/sysctl.conf here to let other have a check. net.ipv4.ip_forward = 0 net.ipv4.conf.default.rp_filter = 1 net.ipv4.conf.default.accept_source_route = 0 kernel.sysrq = 0 kernel.core_uses_pid = 1…
I already have PHP and nginx installed and running on my on Rocky Linux 9. Please guide me, how can install glibc, glibc-common and GD libraries independently on my Rocky Linux 9 without crashing my system? I am not sure how you installed PHP and nginx. If they are installed from CentOS6.7’s Yum repository, you…
Tab widths may be different for different languages. Even with a common language, the tab width settings can be different for different projects. In Vim, are there shortcuts to set tab widths to 2 and 4? To quickly change the tab widths when changing projects. I am afraid no. But you create shortcuts for setting…
In Golang, the fmt.Println() is convenient to print to STDOUT. But how to print string to STDERR? In Go os package, “Stdin, Stdout, and Stderr are open Files pointing to the standard input, standard output, and standard error file descriptors.” So, you can use the WriteString function on File on os.Stderr to print string to…
The dmesg results from newer Linux kernels show the timestamps. It seems the time in seconds since the kernel start time. How to convert the dmesg timestamps to the real time on Linux? The dmesg timestamp is the time in seconds since the kernel starting time. Later dmesg has an -T option: -T, –ctime Print…
How to grep a tab on Linux? Including ‘t’ seems not working. grep can grep tabs. The problem is likely the tab is not passed to grep. If you are using Bash, you can use ANSI-C quoting to pass the “tab” to grep: $ grep $’t’ file.txt Or, use Perl-style regex (only for GNU grep)…
How to get the full path and directory of a Makefile itself like finding Bash script’s own path? This 2 lines in Makefile get the full path and dir of the Makefile itself: mkfile_path := $(abspath $(lastword $(MAKEFILE_LIST))) mkfile_dir := $(dir $(mkfile_path)) The piece of code gets you Makefile, finds its absolute path and the…
How to choose a key used rather than the default ~/.ssh/id_rsa when ssh to a remote server for a specific host? You have at least 2 choices for choosing the key used by ssh. Taking ~/.ssh/key1 and user@example.com as the example here. Method one, specify the key in command line with the -i option of…