Merge pull request #3 from surister/linux_answers
Add new linux answers
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README.md
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README.md
@ -785,9 +785,15 @@ TCP establishes a connection between the client and the server to guarantee the
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You can use the commands <code>cron</code> and <code>at</code>.
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You can use the commands <code>cron</code> and <code>at</code>.
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With cron, tasks are scheduled using the following format:
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With cron, tasks are scheduled using the following format:
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<code>*/30 * * * * bash myscript.sh</code> Executes the script every 30 minutes.
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<minute> <hour> <day of month> <month> <day of week> <command to execute>
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<minute> <hour> <day of month> <month> <day of week> <command to execute>
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The tasks are stored in a cron file.
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The tasks are stored in a cron file.
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Alternatively if you are using a distro with systemd it's recommended to use systemd timers.
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</b></details>
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</b></details>
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<details>
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<details>
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@ -813,9 +819,11 @@ Using the `chmod` command.
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* 644
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* 644
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* 750</summary><br><b>
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* 750</summary><br><b>
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777 - means you are lazy
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<pre>
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644 - owner has read+write permissions and everyone else can only read
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777 - You give the owner, group and other: Execute (1), Write (2) and Read (4); 4+2+1 = 7.
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750 - owner can do anything, group can read and execute and others can do nothing
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644 - Owner has Read (4), Write (2), 4+2 = 6; Group and Other have Read (4).
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750 - Owner has x+r+w, Group has Read (4) and Execute (1); 4+1 = 5. Other have no permissions.
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</pre>
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</b></details>
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</b></details>
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<details>
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<details>
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@ -827,8 +835,23 @@ Using the `chmod` command.
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</b></details>
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</b></details>
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<details>
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<details>
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<summary>What is systemd?</summary><br><b>
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<summary>What is systemd?</summary><br>
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</b></details>
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<b>
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Systemd is a daemon (System 'd', d stands from daemon).
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A daemon is a program that runs in the background without direct control of the user, although the user can at any time
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talk to the daemon.
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systemd has many features such as user processes control/tracking, snapshot support, inhibitor locks..
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If we visualize the unix/linux system in layers, systemd would fall directly after the linux kernel.
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Hardware -> Kernel -> <u>Daemons</u>, System Libraries, Server Display.
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</b>
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</details>
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<details>
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<details>
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<summary>On a system which uses systemd, how would display the logs?</summary>
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<summary>On a system which uses systemd, how would display the logs?</summary>
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