{"id":6708,"date":"2021-08-24T17:04:45","date_gmt":"2021-08-24T11:34:45","guid":{"rendered":"https:\/\/opstree.com\/blog\/\/?p=6708"},"modified":"2026-03-05T17:42:16","modified_gmt":"2026-03-05T12:12:16","slug":"proc-file-system-in-linux","status":"publish","type":"post","link":"https:\/\/opstree.com\/blog\/2021\/08\/24\/proc-file-system-in-linux\/","title":{"rendered":"Proc File System in Linux – An Overview"},"content":{"rendered":"\r\n
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The Proc File System (procfs) in Linux is an innovative, virtual file system located in memory. It serves as a live interface to the kernel’s internal data structures. Instead of keeping data on disk, “files” within procfs are created in real time as they are accessed, providing up-to-date information about the system’s processes, hardware, and overall configuration.<\/p>\r\n

Proc File System in Linux – Complete View<\/h3>\r\n

The proc file system, or procfs, is a dynamic virtual file system that becomes active when the system boots and disappears during shutdown. It serves as a valuable resource, providing information about currently running processes, and as a hub for controlling and relaying information to the kernel. Additionally, the proc file system facilitates communication between kernel space and user space.<\/p>\r\n<\/div>\r\n

I’d like to share an interesting finding with you today. Perhaps, many of you must be already familiar with it but being a newbie, it really intrigued me.<\/p>\r\n

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I have recently enrolled myself in the DevOps Ninja program conducted by my organisation- OpsTree Global<\/strong><\/a>. Everything that I’m learning here is new to me and often amuses me. One day, I was working on an assignment and executed the top<\/strong> command. I left the task as it is and meanwhile started browsing something on the internet. Suddenly a question struck my mind that from where the top command fetches its data ( you can see how I got digressed from my main assignment :p).<\/p>\r\n

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$ top<\/strong><\/p>\r\n

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So, I started exploring (please make note of top <\/strong>command process ID here- 7564) and utilised lsof<\/strong> command to dig deeper.<\/p>\r\n

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$ lsof -p <process id><\/strong><\/p>\r\n

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Here, I happened to find \/proc, <\/strong>went in and found a whole lot of process directories which contained a lot of useful information about system processes and its respective activity history.<\/p>\r\n

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[ Also Read: How to secure your Linux Server<\/a>]<\/strong><\/p>\r\n

WHAT\u2019S \/proc?<\/strong><\/h3>\r\n

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The \/proc directory is present on all Linux systems, regardless of flavor or architecture. The \/proc directory is NOT a real file system but a virtual file system that is created dynamically by Linux to provide access to certain types of hardware information and information about the running processes. It is mapped to \/proc and mounted at boot time.<\/p>\r\n

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To display information about your CPU, you can use the cat \/proc\/cpuinfo <\/strong>command:<\/p>\r\n

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To display information about the file systems supported by currently running Linux kernel:, you can use the cat \/proc\/filesystems <\/em>command:<\/p>\r\n

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To display statistics about memory usage on the system, use the cat \/proc\/meminfo <\/em>command:<\/p>\r\n

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To display the Linux kernel<\/a> version, distribution number and other kernel-related information, use the cat \/proc\/version <\/em>command:<\/p>\r\n

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Within \/proc\u2019s <\/strong>numbered directories, you will find a few files <\/strong>and links<\/strong>. These directories\u2019 numbers correlate to the PID <\/strong>of the command being run within them.<\/p>\r\n

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Let’s check what’s there inside in one of these numbered directories. Here, I chose 2016 and run cat status:<\/em><\/p>\r\n

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In any numbered directory, you will have a similar file structure. The most important ones, and their descriptions, are as follows:<\/p>\r\n

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  1. cmdline <\/strong>\u2013 contains the command that started the process<\/li>\r\n
  2. environ <\/strong>\u2013 contains the names and content of the environment variables for the process<\/li>\r\n
  3. fd <\/strong>\u2013 file descriptors<\/li>\r\n
  4. limits <\/strong>\u2013 contains information about the limits of the process<\/li>\r\n
  5. mounts <\/strong>\u2013 related information<\/li>\r\n<\/ol>\r\n

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    You will also notice a number of links in the numbered directory:<\/p>\r\n

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    1. cwd <\/strong>\u2013 a link to the current working directory of the process<\/li>\r\n
    2. exe <\/strong>\u2013 link to the executable of the process<\/li>\r\n
    3. root <\/strong>\u2013 link to the work directory of the process\u00a0<\/li>\r\n<\/ol>\r\n

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      Just like with the hardware information, you can display the content of these files using the cat command.<\/p>\r\n

      [ Are you looking DevOps Solutions Company<\/a>]<\/strong><\/p>\r\n

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