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--- software:linux:linuxgeneral [2023/10/15 23:05] – removed - external edit (Unknown date) 127.0.0.1
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+====== Disk Usage Analyzer ======
+From: http://www.makeuseof.com/tag/how-to-analyze-your-disk-usage-pattern-in-linux/
+<code>
+Formerly known as Baobab, Disk Usage Analyzer is, as you might have guessed, another visual tool.
+Rather than the block-based approach of QDirStat, this utility offers a radial treemap pie chart
+as a live illustration of disk usage. You’ll find this in the right-hand pane; on the left, a
+list of the contents of the currently selected directory.
+</code>
+====== unprivileged user ======
+From: http://unix.stackexchange.com/questions/22275/how-to-create-an-unprivileged-user-in-centos
+<code>
+useradd (which is the actual binary the runs when you call adduser, it just behaves differently. See here about that.) has an flag -r
+</code>
+From: man: useradd
+<code>
+-r, --system
+Create a system account.
+System users will be created with no aging information in /etc/shadow, and their numeric
+identifiers are chosen in the SYS_UID_MIN-SYS_UID_MAX range, defined in /etc/login.defs,
+instead of UID_MIN-UID_MAX (and their GID counterparts for the creation of groups).
+Note that useradd will not create a home directory for such an user, regardless of the
+default setting in /etc/login.defs (CREATE_HOME). You have to specify the -m options if
+you want a home directory for a system account to be created.
+</code>
+====== Good Description of systemd ======
+From: http://0pointer.de/blog/projects/systemd.html
+<code>
+Process Identifier 1
+On every Unix system there is one process with the special process identifier 1. It is started
+by the kernel before all other processes and is the parent process for all those other processes
+that have nobody else to be child of. Due to that it can do a lot of stuff that other processes
+cannot do. And it is also responsible for some things that other processes are not responsible
+for, such as bringing up and maintaining userspace during boot.
+For a fast and efficient boot-up two things are crucial:
+    To start less.
+    And to start more in parallel.
+</code>
+====== How Do I Convert A SysV Init Script Into A systemd Service File ======
+From: http://0pointer.de/blog/projects/systemd-for-admins-3.html
+create a systemd process service
+<code>
+And that's already it. The entire remaining content of this 115-line shell script is simply boilerplate or otherwise redundant code: code that deals with synchronizing and serializing startup (i.e. the code regarding lock files) or that outputs status messages (i.e. the code calling echo), or simply parsing of the verbs (i.e. the big case block).
+From the information extracted above we can now write our systemd service file:
+[Unit]
+Description=Daemon to detect crashing apps
+After=syslog.target
+[Service]
+ExecStart=/usr/sbin/abrtd
+Type=forking
+[Install]
+WantedBy=multi-user.target
+</code>
+====== systemd-ui ======
+From: http://vazhavandan.blogspot.com/2013/04/graphical-frontend-for-systemd-on.html
+graphical frontend for systemd
+<code>
+zypper install systemd-ui
+systemadm
+</code>
+From: https://www.freedesktop.org/wiki/Software/systemd/
+<code>
+systemd is a suite of basic building blocks for a Linux system. It provides a system and
+service manager that runs as PID 1 and starts the rest of the system. systemd provides
+aggressive parallelization capabilities, uses socket and D-Bus activation for starting
+services, offers on-demand starting of daemons, keeps track of processes using Linux control
+groups, supports snapshotting and restoring of the system state, maintains mount and
+automount points and implements an elaborate transactional dependency-based service
+control logic. systemd supports SysV and LSB init scripts and works as a replacement
+for sysvinit. Other parts include a logging daemon, utilities to control basic system
+configuration like the hostname, date, locale, maintain a list of logged-in users and
+running containers and virtual machines, system accounts, runtime directories and
+settings, and daemons to manage simple network configuration, network time synchronization,
+log forwarding, and name resolution. See Lennart's blog story for a longer introduction, and
+the three status updates since then. Also see the Wikipedia article. If you are wondering
+whether systemd is for you, please have a look at this comparison of init systems by one
+of the creators of systemd.
+</code>
+====== difference between service and systemctl ======
+From: http://forums.fedoraforum.org/showthread.php?t=261945
+<code>
+service operates on the files in /etc/init.d and was used in conjunction with the old
+init system. systemctl operates on the files in /lib/systemd . If there is a file for
+your service in /lib/systemd it will use that first and if not it will fall back to the
+file in /etc/init.d
+</code>
+=== systemctl ===
+From: http://fedoraproject.org/wiki/Systemd
+From: http://crashmag.net/useful-systemd-commands
+=== List the current run level ===
+<code>
+systemctl list-units --type=target
+</code>
+====== Hardware Info ======
+    Grub at higher resolutions?
+    The best achieved is, with vga=0x346
+    Mode 0x0346: 1400x1050 (+5632), 24 bits
+    See what's available with cmd
+    hwinfo --framebuffer
+    also available,
+    Mode 0x0343: 1400x1050 (+1408), 8 bits
+    Mode 0x0345: 1400x1050 (+2816), 16 bits
+====== UNetbootin - Homepage and Downloads ======
+From: http://unetbootin.sourceforge.net/
+    UNetbootin allows you to create bootable Live USB drives for Ubuntu,
+    Fedora, and other Linux distributions without burning a CD. It runs on
+    Windows, Linux, and Mac OS X.
+    Note that resulting USB drives are bootable
+    only on PCs (not on Macs).
+====== Compression ======
+From: http://www.littleigloo.org/linux/how-to/uncompress-linux-files.html
+    Xz is becoming rather popular now-days. For example the official Gnome FTP
+    software archive is now offering for download Xz compressed archives rather
+    than Gzip ones
+====== OpenSuse Reference ======
+From: http://opensuse-guide.org/index.php
+    The purpose of this guide is to provide new users with everything
+    they need to know to get started using openSUSE as a home user/small
+    office desktop operating system - quickly and easily.
+====== Recover - Reset Lost Password ======
+  * Stop Grub Boot by Down arrow key then select default boot option
+  * Type **"e"**
+  * add parameter **"init=/bin/bash"**
+  * **Ctrl-x** to run
+  * after boot **"passwd"**
+  * enter new password and confirm
+  * **QED**
+====== DRBD ======
+From: http://www.drbd.org/download/mainline/
+    integrated into the vanilla Linux kernel with the 2.6.33 release.
+    refers to block devices designed as a building block to form high availability (HA) clusters. This is done by
+    mirroring a whole block device via an assigned network. DRBD can be understood as network based raid-1.
+====== Linux version and Release ======
+    uname -a
+    /etc/issue
+====== Opensuse Firewall Configuration ======
+Trusted Network
+From: http://forums.opensuse.org/english/get-technical-help-here/applications/414092-iptables-allow-certains-ips-block-everyone-else.html
+    You can set that in Yast --> System -> /etc/sysconfig editor --> network --> firewall
+    --> susefirewall2 --> FW_TRUSTED_NETS
+    like so: FW_TRUSTED_NETS="192.168.1.0/24 10.0.0.99" would allow all
+    of the 192.168.1.x series plus the individual IP 10.0.0.99.
+====== Linux Time Conversion ======
+http://www.epochconverter.com/
+    Timestamp in milliseconds: 1365448421000
+    Human time (your time zone): Monday, April 08, 2013 3:13:41 PM
+    Human time (GMT): Mon, 08 Apr 2013 19:13:41 GMT
+    Timestamp in milliseconds: 1365426815000
+    Human time (your time zone): Monday, April 08, 2013 9:13:35 AM
+    Human time (GMT): Mon, 08 Apr 2013 13:13:35 GMT
+    Timestamp in milliseconds: 1364598852000
+    Human time (your time zone): Friday, March 29, 2013 7:14:12 PM
+    Human time (GMT): Fri, 29 Mar 2013 23:14:12 GMT
+    Timestamp in milliseconds: 1364577144000
+    Human time (your time zone): Friday, March 29, 2013 1:12:24 PM
+    Human time (GMT): Fri, 29 Mar 2013 17:12:24 GMT
+    Timestamp in milliseconds: 1363978800000
+    Human time (your time zone): Friday, March 22, 2013 3:00:00 PM
+    Human time (GMT): Fri, 22 Mar 2013 19:00:00 GMT
+    Timestamp in milliseconds: 1364014800000
+    Human time (your time zone): Saturday, March 23, 2013 1:00:00 AM
+    Human time (GMT): Sat, 23 Mar 2013 05:00:00 GMT
+    Timestamp in milliseconds: 1364081400000
+    Human time (your time zone): Saturday, March 23, 2013 7:30:00 PM
+    Human time (GMT): Sat, 23 Mar 2013 23:30:00 GMT
+    Timestamp in milliseconds: 1364117400000
+    Human time (your time zone): Sunday, March 24, 2013 5:30:00 AM
+    Human time (GMT): Sun, 24 Mar 2013 09:30:00 GMT
+====== Cron Messages ======
+Suse 10.x in %%/var/log/messages%%
+====== Cron ======
+<code>
+#|   hour (0-23)
+#|   |    day of the month (1-31)
+#|   |    |   month of the year (1-12 or Jan-Dec)
+#|   |    |   |   day of the week (0-6 with 0=Sun or Sun-Sat)
+#|   |    |   |   |   user
+#|   |    |   |   |   |   commands
+#|   |    |   |   |   |   |
+# Each line has five time-and-date fields
+# followed by a username (if this is the system crontab file),
+# and followed by a command.
+# 20   1    1   *   *  smolt /usr/bin/smoltSendProfile -c > /dev/null 2>&1
+# top of every other hour :0
+   */2   *    *   *    root /root/Desktop/own-p  > /var/log/own-p.log 2>&1
+</code>
+====== BAD FILE MODE ======
+From: http://www.cyberciti.biz/faq/unix-linux-cron-bad-file-mode-error/
+<code>
+    All you have to do it set 0644 (rw-r--r) permission i.e. remove world writable
+    file permissions
+From: http://old-en.opensuse.org/Packaging/SUSE_Package_Conventions/Cron_Jobs
+    As defined in /etc/crontab, cron executes the script /usr/lib/cron/run-crons
+    every 15 minutes. It looks for scripts in the directories /etc/cron.{hourly,
+    daily,weekly,monthly} and checks which should be executed. The information about
+    last run is stored in files below /var/spool/cron/lastrun.
+</code>