C2110 UNIX and programming Lesson 2 / Module 2 -1C2110
UNIX and programming
Petr Kulhanek
kulhanek@chemi.muni.cz
National Center for Biomolecular Research, Faculty of Science
Masaryk University, Kamenice 5, CZ-62500 Brno
Lesson 2 / Module 2
PS / 2020 Distance form of teaching: Rev2
C2110 UNIX and programming Lesson 2 / Module 2 -2-
Commands
➢ Manual pages
➢ Basic detection commands
C2110 UNIX and programming Lesson 2 / Module 2 -3Command
Help
Manuals sites (or what to do, when I get lost):
man lists manual page of given command
$ man [section_number] stoker
Available sections:
❑ Section 1 user commands
❑ Section 2 system calls
❑ Section 3 library functions
❑ Section 4 special files
❑ Section 5 file formats
name of command, function, topic, chapter etc.
Number of the section must be entered for topics with the same name included in different sections.
❑ Section 6 games
❑ Section 7 conventions and miscellany
❑ Section 8 administration and privileged commands
❑ Section L math library functions
❑ Section N tcl functions
$ man 1 printf
$ man 3 printf
man page of the printf command
C page printf() man page
C2110 UNIX and programming Lesson 2 / Module 2 -4Help,
Searching for Commands
Navigation in the help text:
● scroll through the text (up and down arrow keys or j and k)
● scroll through the text (PgDn and PgUp or keys f and b)
● search ( /search_text , key n for further search)
● close help (key q)
Online manual pages in HTML format:
http://linux.die.net/man/
Useful commands:
whatis lists short command description (from the manual page)
apropos searches for commands that contain the specified keyword in the manual
info displays of info pages of a command (similar to manual pages)
C2110 UNIX and programming Lesson 2 / Module 2 -5Description/Entering
Commands
$ command [options] [-] [arguments]
short options
-a
-as or -a -s
-f file.txt
long options
--file file.txt
end of entering options must be used only
in very special cases, it is not used
commonly
arguments
main data or information passed to
the command
must be listed in a specific order
[] means optional options or arguments
<> means mandatory options or arguments, alternatively can be given without parentheses
extend/change the behavior of the command
can usually be listed in any order
C2110 UNIX and programming Lesson 2 / Module 2 -6Detection
Commands
man manual pages of commands
whatis prints a short description of the command (from the manual page)
by the way searches for commands that contain the keyword specified in the label in the
manual
info display info command pages (similar to manual pages)
whoami lists the name of the logged in user
hostname lists the name of the machine you are logged in to
id lists the identification data of the logged in user and his grouping
w lists who is logged in to the machine and what it does
who lists who is logged in to the machine
ps lists running processes
top monitors running processes
loginctl manages environment-managed sessions systemd (statement, termination, etc.)
last lists the most recently logged in users
C2110 UNIX and programming Lesson 2 / Module 2 -7Exercise
1
1. Log in to the wolf02.ncbr.muni.cz node
2. Find the man pages in section 1 that contain the keyword directory or
directories. Which command is used to create directories?
3. What is the full name of your computer (command hostname and selection
according to the manual pages).
4. Enter your login name with the command whoami.
5. What is your identification number (uid)?
6. Find out who is logged on to the wolf02 workstation with the command w and
who.
7. What is the difference between commands w and who according to manual
pages or command whatis?
8. List the session using the command loginctl and last. What is the difference
between them?
9. Get an overview of running processes with the command top (the command is
terminated by pressing the q key).