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Mainframe operating systems Server operating systems Multiprocessor operating systems Personal computer operating systems Real-time operating systems Embedded operating systems Smart card operating systems

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While the log files found in /var/log may be extremely helpful for troubleshooting problems, they might become a problem themselves if they fill up the filesystem. Having services like mail and printing available may be useful, but if they cause your system to crash, then that can be a problem. Mounting /var on a separate partition is often done ...

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To display the current umask value, execute umask with no arguments. To set umask to a value of 027, type umask 027 The new umask value will only apply during a login session. When a new shell is started, your default umask will be in effect again. To set a new default umask, modify ~/.bashrc The umask value has no effect on existing files or ...

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Use the userdel command to delete a user account. By default, only the account is deleted, not any of the files owned by the user. By using the –r option, files in the user’s home directory and the user’s mail spool are deleted.

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Displays detailed user and system information: [sysadmin@localhost ~]$ w 10:44:03 up 50 min, 4 users, load average: 0.78, 0.44, 0.19 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT root tty2 - 10:00 43:44 0.01s 0.01s -bash sysadmin tty1 :0 09:58 50:02 5.68s 0.16s id sysadmin pts/0 :0.0 09:59 0.00s 0.14s 0.13s who sysadmin pts/1 example.com 10:00...

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ifconfig - Displays interface configuration information. route - Displays the routing table. ping - Used to determine if a remote machine can be contacted via the network. netstat - Display network statistics. dig - Displays query results from DNS servers. ssh - Allows a user to login to a remote machine.

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The kernel ring buffer is memory used to hold messages generated by the kernel. The /var/log/dmesg file is used by some distributions to hold kernel messages that were generated during start up. Kernel messages, mixed in with other messages, are found in the /var/log/messages or /var/log/syslog file. The /etc/syslog.conf or /etc/rsyslog.conf fil...

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No video standards, requiring specific drivers for specific video cards. Two types of connections: Video Graphics Array (VGA) Digital Visual Interface (DVI) Monitor and video card must both support selected resolution. Typically X.org server determines proper resolution.

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Tests the loop condition each time while [ ! –f /tmp/foo ]; do try_to_make_foo # makes /tmp/foo on success sleep 1 # wait 1 sec done Used when the number of loops is unknown or changes each loop

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The xargs command helps complex piped command sets execute more efficiently It attempts to build the longest command line possible with as many arguments as possible It tries to prevent executing the command each time for every argument

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