Unix Tutorial

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console cron daemon ftp kern local0.local7 lpr mail mark news ntp user Used to capture messages that would generally be directed to the system console Messages from the cron system scheduler System daemon catch-all Messages relating to the ftp daemon Kernel messages Local facilities defined per site Messages from the line printing system Messages relating to the mail system Pseudo event used to generate timestamps in log files Messages relating to network news protocol (nntp) Messages relating to network time protocol Regular user processes uucp UUCP subsystem Syslog Priorities: The syslog priorities are summarized in the following table: Priority Emerg Alert Crit Err Warning Notice Info Debug None Description Emergency condition, such as an imminent system crash, usually broadcast to all users Condition that should be corrected immediately, such as a corrupted system database Critical condition, such as a hardware error Ordinary error Warning Condition that is not an error, but possibly should be handled in a special way Informational message Messages that are used when debugging programs Pseudo level used to specify not to log messages. TUTORIALS POINT Simply Easy Learning
The combination of facilities and levels enables you to be discerning about what is logged and where that information goes. As each program sends its messages dutifully to the system logger, the logger makes decisions on what to keep track of and what to discard based on the levels defined in the selector. When you specify a level, the system will keep track of everything at that level and higher. The /etc/syslog.conf file: The /etc/syslog.conf file controls where messages are logged. A typical syslog.conf file might look like this: *.err;kern.debug;auth.notice /dev/console daemon,auth.notice /var/log/messages lpr.info /var/log/lpr.log mail.* /var/log/mail.log ftp.* /var/log/ftp.log auth.* @prep.ai.mit.edu auth.* root,amrood netinfo.err /var/log/netinfo.log install.* /var/log/install.log *.emerg * *.alert |program_name mark.* /dev/console Each line of the file contains two parts: A message selector that specifies which kind of messages to log. For example, all error messages or all debugging messages from the kernel. An action field that says what should be done with the message. For example, put it in a file or send the message to a user's terminal. Following are the notable points for the above configuration: Message selectors have two parts: a facility and a priority. For example, kern.debug selects all debug messages (the priority) generated by the kernel (the facility). Message selectetor kern.debug selects all priorities that are greater than debug. An asterisk in place of either the facility or the priority indicates "all." For example, *.debug means all debug messages, while kern.* means all messages generated by the kernel. You can also use commas to specify multiple facilities. Two or more selectors can be grouped together by using a semicolon. Logging Actions: The action field specifies one of five actions: 1. Log message to a file or a device. For example, /var/log/lpr.log or /dev/console. 2. Send a message to a user. You can specify multiple usernames by separating them with commas (e.g., root, amrood). 3. Send a message to all users. In this case, the action field consists of an asterisk (e.g., *). 4. Pipe the message to a program. In this case, the program is specified after the UNIX pipe symbol (|). 5. Send the message to the syslog on another host. In this case, the action field consists of a hostname, preceded by an at sign (e.g., @tutorialspoint.com) TUTORIALS POINT Simply Easy Learning
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Unix Tutorial
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ABOUT THE TUTORIAL Unix Tutorial UN
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Renaming Directories: .............
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Extended Shell Scripts: ...........
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Example: ..........................
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Trapping Signals: .................
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The main concept that unites all ve
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New UNIX password:******* Retype ne
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CHAPTER 2 Unix File Management All
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Displays all the files whose name s
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4. Fourth Column: represents file n
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CHAPTER 3 Unix Directories Adirecto
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Creates the directories docs and pu
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CHAPTER 4 Unix File Permission Setu
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$ls -l testfile -rw-rwxrwx 1 amrood
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The SUID and SGID bits will appear
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Note - The shell initialization pro
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The default secondary prompt is > (
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CHAPTER 6 Java Basic Utilities So f
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laserp-574 grace 82744 Nov 7 11:28
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CHAPTER 7 Unix Pipes and Filters Yo
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This pipe sorts all files in your d
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The process runs in the foreground,
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$kill -9 6738 Terminated Parent and
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CHAPTER 9 Unix Communication When y
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prompt on Turns prompt on. Dir List
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No Plan. Check all the logged in us
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~ ~ ~ ~ ~ ~ ~ ~ "testfile" [New Fil
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Command CTRL+d CTRL+d CTRL+f CTRL+u
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^G U U J Press CNTRL and G keys at
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IMPORTANT: Here are the key points
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POSIX shell ( sh) The different C-t
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CHAPTER 12 Unix- Using Variables Av
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NAME="Zara Ali" unset NAME echo $NA
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Command-Line Arguments: The command
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CHAPTER 14 Unix - Using Arrays Ashe
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CHAPTER 15 Unix - Basic Operators T
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val=`expr $b / $a` echo "b / a : $v
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else echo "$a -ge $b: a is not grea
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!= Checks if the value of two opera
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] is true. -x file Check if file is
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Right shift == String comparison fo
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-r file Checks if file is readable
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Page 91 and 92: CHAPTER 17 Unix - Shell Loops Loops
Page 93 and 94: done This will produce following re
Page 95 and 96: 4) juice 5) appe 6) all 7) none #?
Page 97 and 98: CHAPTER 18 Unix - Loop Control So f
Page 99 and 100: 1 0 1 5 The continue statement: The
Page 101 and 102: \n new line \r carriage return \t h
Page 103 and 104: CHAPTER 20 Unix - Quoting Mechanism
Page 105 and 106: The Double Quotes: Try to execute t
Page 107 and 108: CHAPTER 21 Unix - IO Redirections M
Page 109 and 110: EOF 3 $ This is a simple lookup pro
Page 111 and 112: CHAPTER 22 Unix - Shell Functions F
Page 113 and 114: echo "Return value is $ret" This wo
Page 115 and 116: CHAPTER 23 Unix - Manpage Help All
Page 117 and 118: CHAPTER 24 Unix - Regular Expressio
Page 119 and 120: Try out the following address range
Page 121 and 122: sys:x:3:3:sys:/dev:/bin/sh sync:x:4
Page 123 and 124: [0-9] Matches a single number [a-zA
Page 125 and 126: (555)555-1213 (555)555-1214 (666)55
Page 127 and 128: dev /etc /lib /boot /home /mnt /pro
Page 129 and 130: $du -h /etc 5k /etc/cron.d 63k /etc
Page 131 and 132: CHAPTER 26 Unix - User Administrati
Page 133 and 134: $ groupdel developer This removes o
Page 135 and 136: CHAPTER 27 Unix - System Performanc
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Page 141 and 142: Unix - Signals and Traps CHAPTER 29
Page 143 and 144: Trapping these signals is quite eas
Page 145 and 146: CHAPTER 30 Unix - Useful Commands T
Page 147 and 148: Ispell Emacs ex, edit Emacs Emacs C
Page 149 and 150: Command Dbx Gdb Make Nm Size Strip
Page 151 and 152: Reset Reset terminal mode Script Ke
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