Discover DevOps roles and learn Linux from basics to advanced at DevOpsRoles.com. Detailed guides and in-depth articles to master Linux for DevOps careers.
tail command means Print the last 10 lines of each FILE to standard output.
tail [OPTION]… [FILE]…
On the man page, the describes it
$ tail devopsroles.log
$ tail -f devopsroles.logtail command is a simple command in Linux. It is the most popular in use terminal Linux output the last part of files. Thank you for reading the DevopsRoles page!
cat command means Concatenate file(s), or standard input, to standard output.
cat [OPTION]… [FILE]…
On the man page, the describes it
$ cat devopsroles.txt
$ cat -n devopsroles.txtcat command is a simple command in Linux. It is the most popular in use terminal Linux concatenate files and print on the standard output. Thank you for reading the DevopsRoles page!
vi command means Open a text editor.
vi [-eFRrS] [-c cmd] [-t tag] [-w size] [file …]
On the man page, the describes it
$ vi devopsroles.txtvi is a simple command in Linux. It is the most popular in use terminal Linux Vi has three main modes Command mode, Insert mode and Command-Line mode. Thank you for reading the DevopsRoles page!
sudo command in Linux means sudo allows a permitted user to execute a command as the superuser or another user, as specified by the security policy.
sudo -V | -h | -l | -L | -v | -k | -K | -s | [ -H ] [-P ] [-S ] [ -b ] |
[ -p prompt ] [ -c class|- ] [ -a auth_type ] [-r role ] [-t type ]
[ -u username|#uid ] command
On the man page, the describes it
$ sudo yum install nginxsudo is a simple command in Linux. It is the most popular in use terminal Linux execute a command as another user. Thank you for reading the DevopsRoles page!
This guide will walk you through the ins and outs of using the man command in Linux, complete with examples, tips, and answers to common questions.
Linux is a versatile operating system that caters to users of all skill levels, from beginners to seasoned experts. One of its most powerful tools for understanding and utilizing commands effectively is the man command. Short for “manual,” the man command provides comprehensive documentation for nearly every tool and command in Linux. Whether you’re troubleshooting, exploring new commands, or fine-tuning your workflow, mastering the man command is essential.
man Command?The man command is a built-in tool in Linux that displays the manual pages (man pages) for other commands and utilities. It serves as a comprehensive reference, offering detailed information about a command’s syntax, options, and examples.
The basic syntax for the man command is:
man [-acdfFhkKtwW] [–path] [-m system] [-p string] [-C config_file] [-M pathlist] [-P pager] [-B browser] [-H htmlpager] [-S section_list] [section] name …
On the man page, the describes it
$ man man
$ man freeTo view the manual page for a command like ls, run:
man ls
Once inside a manual page:
q to quit the manual page./ followed by a search term to find specific text.Linux manual pages are divided into numbered sections. For example, to view the manual page for the open system call in section 2:
man 2 open
Linux man pages are divided into sections based on their content. Here are the most commonly used sections:
If you’re unsure which command to use, search by keyword with the -k option:
man -k "keyword"
For example, to find all commands related to “disk”:
man -k disk
Sometimes, a command has entries in multiple sections. Use the -a option to view all related sections:
man -a open
To print or save a manual page, use the -t option:
man -t ls | lpr
man OutputChange the default pager for man pages by setting the PAGER environment variable:
export PAGER=less
grep CommandTo learn about grep, a powerful text-searching tool:
man grep
The manual explains:
-i for case-insensitive searches.To explore how to use strace for debugging:
man strace
Learn to trace system calls and signals of a process.
Check the manual for bash to build robust shell scripts:
man bash
man command is not found?Ensure the man package is installed. On Debian-based systems, use:
sudo apt install man-db
The man command does not directly show versions. Use the --version option of the command, e.g., ls --version.
Yes, many Linux distributions provide online manuals, such as man7.org.
Use / followed by your search term, then press Enter. Navigate through matches using n for next and N for previous.
Update the MANPATH environment variable to include the directory of the manual pages.
man is a simple command in Linux. It is the most popular in use terminal Linux format and displays the on-line manual pages. Thank you for reading the DevopsRoles page!
The free command in Linux is a fundamental tool, providing an instant snapshot of system memory usage. Whether you’re a system administrator troubleshooting performance issues or a curious user monitoring resource allocation, mastering the free command is essential. In this guide, we will explore its functionality, explain its output, and provide practical examples to make you proficient in using this powerful tool.
The free command is part of the GNU core utilities, offering a concise view of memory usage, including:
By interpreting its output, you can make informed decisions about memory optimization, application performance, and system health.
When you run the free command, you’ll see several important metrics:
The basic syntax for the free command is straightforward:
free [options]
On the man page, the describes it
Here are the most commonly used options with the free command:
-b, -k, -m, -g: Display output in bytes, kilobytes, megabytes, or gigabytes.-h: Human-readable format (e.g., “2.5G” instead of “2621440”).-s [seconds]: Continuously display memory usage at specified intervals.-t: Show total memory, including swap and physical memory.To display memory usage in a readable format:
free -h
Output:
total used free shared buff/cache available
Mem: 15Gi 8Gi 2Gi 1Gi 4Gi 6Gi
Swap: 4Gi 1Gi 3Gi
To track memory usage every 2 seconds:
free -h -s 2
Include the total memory line with:
free -t
View memory statistics in gigabytes for clarity:
free -g
Create a script to log memory usage:
#!/bin/bash
while true
do
free -h >> memory_log.txt
sleep 60
done
Save this script as memory_monitor.sh, make it executable, and run it in the background:
chmod +x memory_monitor.sh
./memory_monitor.sh &
free with System Monitoring ToolsCombine free with tools like top or htop for a holistic view of system performance. For example:
watch -n 1 free -h
The “available” column shows the amount of memory that applications can use without swapping. It’s a more reliable indicator than “free” for assessing system health.
Linux uses free memory for buffers and cache to improve performance. This memory is available for applications if needed.
Use the following command to free up cache memory (requires root privileges):
sync; echo 3 > /proc/sys/vm/drop_caches
free command available on all Linux distributions?Yes, the free command is part of the procps-ng package, which is included in all major Linux distributions.
For further reading and advanced configurations, check out the following authoritative sources:
freefree command is a simple command in Linux. It is the most popular in use terminal Linux Display amount of free and used memory in the system. Thank you for reading the DevopsRoles page!
du command means Disk usage.
du [OPTION]… [FILE]…
du [OPTION]… –files0-from=F
On the man page, the describes it
$ du -shdu command is a simple command in Linux. It is the most popular in using terminal Linux estimate file space usage. Thank you for reading the DevopsRoles page!
In this tutorial, How to use the ls command in Linux with Examples. In the Linux ecosystem, the ls command is a cornerstone utility for managing and navigating files and directories. Whether you are a beginner exploring the Linux command line or a seasoned sysadmin managing complex systems, understanding how to leverage ls effectively is essential. This article provides a comprehensive look at the ls command, ranging from basic usage to advanced options, making it a must-read for anyone seeking to enhance their Linux expertise.
The ls command is used to list files and directories in Linux. Its simplicity and versatility make it one of the most commonly used commands in the Linux shell. By displaying directory contents, ls helps users manage files, analyze storage structures, and perform quick verifications of directory states.
ls [OPTION]… [FILE]…
On the man page, the describes it
$ ls -l
$ ls -a
$ lsHow to display file timestamps use the option ‘–time-style’
ls -l --time-style="+%Y-%m-%d %H:%M:%S" /home/vagrant
List only directory with option ‘-ld’
ls -ld /home/vagrant
List file recursively
ls -lR /home/vagrant/kubekey
List files with size.
ls -s /home/vagrant/
ls command stand for?ls stands for “list” and is used to display the contents of a directory.
ls to list files in another directory?Yes, specify the directory path:
ls /path/to/directory
Use the --color option:
ls --color=auto
Files starting with a dot (.) are hidden. Use ls -a to view them.
Use:
ls -lt
ls options in your shell configuration file (e.g., .bashrc):
alias ll='ls -lh'ls with other utilities like grep or awk for advanced processing.ls command is a simple command in Linux. It is the most popular in use terminal Linux list directory contents. Thank you for reading the DevopsRoles page!
chown command means Change an owner of a file and/or the group the file is associated with.
chown [OPTION]… [OWNER][:[GROUP]] FILE…
chown [OPTION]… –reference=RFILE FILE…
On the man page, the describes it
$ chown huupv:huupv mydevops.txtchown command is a simple command in Linux. It is the most popular in use terminal Linux change file owner and group. Thank you for reading the DevopsRoles page!
chgrp command means Changes the group association of the files and directories.
chgrp [OPTION]… GROUP FILE…
chgrp [OPTION]… –reference=RFILE FILE…
On the man page, the describes it
$ chgrp -hR huupv mydevops.txtchgrp command is a simple command in Linux. It is the most popular in use terminal Linux remove files or directories. Thank you for reading the DevopsRoles page!