Question

Choose 10 commands from the list to study in detail for this assignment. For each command, you need to provide a short description of the main functionality, and an example run (including output) of the command.

Notes

•  You need to choose at least one command from each category.

•  Be brief. You do not need to write a lot.

•  Although you are only required to document the usages of 10 commands in this assignment,

  you are expected to know all the commands for this course (in particular, exams).

  Process management and status 1. at

  2. bg
  3. crontab 4. fg
  5. kill
  6. nice
  7. nohup 8. ps
  9. sudo 10. suspend 11. time
  12. top

  File and directory 13. cat

  14. chgrp 15. chmod 16. chown 17. cd

  18. cp 19. dd 20. diff 21. dirs 22. file 23. find 24. grep 25. head 26. less

27. ln
28. ls
29. mkdir 30. mv 31. popd 32. pushd 33. pwd 34. size 35. tail 36. touch 37. umask 38. wc

User management and information 39. id

40. groups
41. limit (or ulimit) 42. makepasswd 43. passwd
44. su

Networking 45. arp 46. dig

47. ifconfig 48. hostname 49. nc
50. netstat 51. nslookup 52. ping
53. route
54. ssh
55. traceroute 56. wget

Programming tools 57. ddd

58. gdb 59. make 60. nm
61. strace 62. strings

Machine and system status
63. /proc/cpuinfo (this and the next are not commands, but files. You can “cat” their contents)64. /proc/meminfo
65. df
66. du
67. free
68. sysinfo
69. uptime
70. uname
71. vmstat

Other utilities 72. bc
73. cal

74. clear 75. crypt 76. cut 77. date 78. env 79. ispell 80. sort 81. tar 82. tr

83. uniq 84. xargs

Answer 1

1. kill:

The killcommand in unix/linux is used to send a signal to a process. If no message is specified, TERM signal is sent and the process is terminated.

Usage: kill pid where pid is the process ID.

Output: None

2. cat:

The cat command is short for concatenate. This is one of the powerful linux file operation command which is used to create single or multiple files, view contain of file, concatenate files and redirect output in terminal or files.

Usage: cat filename

Output: The contents of the file

3. ls:

ls is a command which lists the directory files and directories.

Usage: ls [options] [file|dir]

Output: List of files and directories according to the options given.

4. su:

The su command is an acronym for "substitute user". It makes possible for changing the login session's owner.

Usage: su [options] [commands] [-] [username]

Output: Changes the owner.

5. pwd:

The pwd command is used to print the full system path of the current working directory.

Usage: pwd

Output: Full system path of the current working directory.

6. chmod:

chmod command is used to set permissions of files and directories.

Usage: chmod [options] [permissions] [file name]

The permissions can be given in terms of rwx or numbers such as 777/755

Output: File with required permissions

7. ifconfig:

ifconfig(interface configuration) command is used to configure the kernel-resident network interfaces.

Usage: ifconfig [options] [interface]

Output: List of network interfaces accordingly with options.

8. date:

This command shows the current system time.

Usage: date

Output: Tue Sep 17 21:27:49 CT 2019

9. env:

This command is used to run a program in a different modified environment

Usage: env [option]... [-] [name=value]... [command[arg]]

Output: When only env is used, it shows all the environment variables.

10. uname:

The uname command displays system information.

Usage: uname [options]

Output: Displays system information