1. who and w
To find out which users are logged into the machine as well as yourself, type who. This command comes with many options. Read the man pages to find out more. The output of who comprises several columns. The first column gives the userid's of all users logged in, the second column lists the terminal where each user is logged in, the next few columns give the date and time when each user logged in, and the final column gives the network address of each user. Below is typical output for the who command:
cudcu pts/5 Aug 2 10:22 (mimosa) eosbab pts/43 Jan 27 07:48 (curiousyellow) phrjf pts/9 Aug 12 15:18 (bogwort.theory.warwick.ac.uk) eosbab pts/10 Aug 30 07:54 (lorretta) marxaj pts/11 Aug 24 09:04 (sajama.maths.warwick.ac.uk) phsday pts/90 Jul 14 08:10 (kalyke.theory.warwick.ac.uk) stsbm pts/58 Aug 30 09:57 (kiki) cudau pts/113 Jul 14 10:17 (flaky)
You can go further than this and use another command, w, to find out what current process each user is running on a given machine. Again, just type w at the terminal and hit return. The output is similar, except now there are some columns giving CPU time used, as well as the name and arguments of each current process (under the heading what. Below is typical output for the w command:
User tty login@ idle JCPU PCPU what aosaaf pts/31 10Mar05 2days 13:38 13:38 ssh primrose ccscab pts/36 11:39pm 11:42 2 2 pine -i cudcu pts/27 2Aug0528days 2:03 2:03 mutt -f /home/unit/cu/dcu/Mail/r phsday pts/46 14Jul05 1:47 2:27 1 -tcsh mssbal pts/50 8:47am 24 12 w helpdesk pts/51 8:48am 12 1 pine -i cudcu pts/34 19Jul0525days 5:53 -tcsh cusbae pts/56 20Aug05 10:51 1:09 25 pine -f MAILBOX -i helpdesk pts/64 8:19am 19 8 pine -i pssbx pts/67 11:14am 12 pine cudbu pts/52 8:55am 9 34 30 /package/StarOffice/sparc/Office
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2. Getting the time and date
To get the current time and date as set for your machine, just type date and hit return.
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3. Displaying a calendar
You can display the calendar for the current month this year (or at least according to the date your machine is set for), by typing cal and hitting return.
cal comes with a few options. Typing cal -y outputs the calendar for the entire current year. Typing cal year, you can display the calendar for any given year.
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4. Setting job priorities
When you launch a job from the command line, you can set the priority by using the command nice . the basic syntax of this command is:nice priority number command
where priority number can range between 1 and 19 (see Section 1.10.3 to remind yourself about job priority).