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See this page as a slide show

Unix Commands III

CS155 Commands4

Time Commands

$ date
Thu Nov 21 09:47:27 MST 2024
$ cal
    November 2024   
Su Mo Tu We Th Fr Sa
                1  2
 3  4  5  6  7  8  9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
                    
$ cal 11 1957
    November 1957   
Su Mo Tu We Th Fr Sa
                1  2
 3  4  5  6  7  8  9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
                    

• date - Display the current date and time
• cal - display a simple calendar
  • -3 - Display previous, current, and next month
  • -y - Display a calendar for the year

System Commands

• uptime - information on system load, number of users, and uptime
• who - list of users currently logged in
• w - combination of uptime and who

11:32:19 up 9 days, 17:43,  3 users,  load average: 0.00, 0.00, 0.00
  USER     TTY        LOGIN@   IDLE   JCPU   PCPU WHAT
  cs155    pts/0     11:32    0.00s  0.08s  0.00s w
  applin   pts/1     11:32   14.00s  0.08s  0.08s -bash

Finding Things in the Filesystem

• When you execute a command or program, Unix search a list of paths for the executable file.
• which - give the full path of an executable

% which cat
/bin/cat

• whereis - search all common executable directories for binaries (executable files), man pages, source files.

% whereis date
date: /usr/bin/date /usr/share/man/man1p/date.1p.gz /usr/share/man/man1/date.1.gz

find

• find – searches the file system for a file or files based on name, size, when changed, etc.
• Usage: find path expression
• find searches recursively from path down looking for files that match expression.

find: Common Expressions

find -name pattern : search for files with name matching pattern. Pattern uses wildcard symbols.

% find ~/pub/ -name '*.t??'
/s/bach/a/class/cs155/pub/dwarfs.txt
/s/bach/a/class/cs155/pub/hw3.tgz
/s/bach/a/class/cs155/pub/domains.txt

• find . -name html
  Search for directories named exactly html
• find . -name "*html"
  Search for files and directories ending with html

find: Common Expressions

• -user username : file is owned by username
• Time-based:
  • -amin -n : file access up to n minutes ago
  • -mtime -n : file was last modified up to n days ago

% find ~/pub/ -user cs155 -name 'jack.*'
/s/bach/a/class/cs155/pub/hw2Files/jack.info
/s/bach/a/class/cs155/pub/hw2Files/jack.log
/s/bach/a/class/cs155/pub/hw2Files/jack.jpg
/s/bach/a/class/cs155/pub/hw2Files/jack.grades

find: Actions

• We can specify actions for find to perform on each file it finds.
  • -delete : delete found files (life in the fast lane)
  • -ls : give full listing of files
  • -exec command : run command on files

% find . -mtime -1 -ls
8798609 12 drwx--x--x  84 applin   fac  12288 Jan  1 16:43 .
8799248  4 -r--------   1 applin   fac    395 Jan  1 17:01 ./monster
1246232  4 drwxrwxr-x   3 applin   fac   4096 Jan  1 16:43 ./public_html/wiki/cookbook

find . -name "*.bak" -exec mv {} old \;

Search for a string in a selection of files (executing grep):

find . -exec grep "Boese" '{}' \; -print

find: exec

• The -exec action can be very handy.
• Everything after -exec is considered part of the command to execute until a ; is encountered. The ; must be escaped by using \ because it is a special character in the shell.
• All occurrences of {} are replaced by the full path to the found file.

Miscellaneous Commands

• uname – print system information
  • -a : print all information

% uname -a
Linux beethoven 4.18.0-553.22.1.el8_10.x86_64 #1 SMP Tue Sep 24 05:16:59 EDT 2024 x86_64 x86_64 x86_64 GNU/Linux

• su - switch user (login in as different user)
• whoami – get current user name

% whoami
cs155

• touch – change access and modification times of files
• bc – Basic Calculator

Miscellaneous Commands 2

• ispell – spell check a file
• ping – check whether another computer is alive

% ping -c1 denver
PING denver.cs.colostate.edu (129.82.44.141) 56(84) bytes of data.
64 bytes from denver.cs.colostate.edu (129.82.44.141): icmp_seq=1 ttl=64 time=0.396 ms

--- denver.cs.colostate.edu ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.396/0.396/0.396/0.000 ms

Printing in Unix

• At CSU, printers are usually not connected directly to a computer.
• They’re connected to the network, and can be accessed from any computer.
• Printers have names, like anything else connected to the network.
• The printer near my office is called kazoo or kazoo.cs.colostate.edu.
• A printer in the Linux Lab is called tuba.

A list of CS department printers: https://www.cs.colostate.edu/~info/printers

Print Commands

• lpr – send file to printer without formatting
  • -Pprinter : sent to printer
  • lpr -Ptuba my_file
• lpq – list the printer queue
  • printers are first come, first served
  • lpq -Ptuba
• lprm – remove print job
  • lprm -Ptuba 452

Print Commands

% lpr -Ptuba my_file
% lpr -Ptuba my_file2
% lpq -Ptuba
tuba is ready and printing
Rank    Owner   Job   File(s)               Total Size
active  applin  1016  my_file               1944576 bytes
1st     xhua    1021  (stdin)               12432 bytes
2nd     applin  1028  my_file2              134144 bytes
% lprm -Ptuba 1028
% lpq -Ptuba
tuba is ready and printing
Rank    Owner   Job   File(s)               Total Size
active  xhua    1021  (stdin)               12432 bytes

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