UnixCmds

UNIX COMMANDS

 

UNIX commands: 

1. To create a directory.
   1. Syntax :  mkdir <directory name>
   2. Example :  mkdir oslab
2. To rename a directory.
   1. Syntax :  mv <directory 1> <directory 2>
   2. Example :  mv CIVIL IT
3. To change the directory.
   1. Syntax :  cd <directory name>
   2. Example :  cd IT1
4. To copy the directory and its file to another directory.
   1. Syntax :  cp –r <source directory> <destination directory>
   2. Example :  cp –r IT1/ IT2
5. To remove an empty directory.
   1. Syntax :  rmdir <empty directory name>
   2. Example :  rmdir IT1
6. To remove an non–empty directory.
   1. Syntax :  rmdir –r <directory name>
   2. Example :  rmdir –r IT2
7. To print present working directory. / To display complete path of the working directory.
   1. Syntax :  pwd
8. To create a file.
   1. Syntax :  vi <file name>
   2. Example :  vi aa.txt
9. To rename a file.
   1. Syntax :  mv <old file name> <new file name>
   2. Example :  mv aa.txt a1.txt
10. To view a file.
    1. Syntax :  cat <file name>
    2. Example :  cat a1.txt
11. To copy files.
    1. Syntax :  cp <source filename> <destination filename>
    2. Example :  cp a1.txt a2.txt
12. To move files.
    1. Syntax :  mv <filename 1> <filename 2>
    2. Example :  mv a1.txt a2.txt
13. To concatenate two files.
    1. Syntax :  cat <file 1> <file 2>  > <new file 3>
    2. Example :  cat a1.txt a2.txt > a3.txt
14. To display the file contents.
    1. Syntax :  cat <file name>
    2. Example :  cat a3.txt
15. To display the file contents with line number.
    1. Syntax :  cat –n <file name>
    2. Example :  cat –n a3.txt
16. To create a file using cat command
    1. Syntax : cat > <filename>

<Type the information and press <ctrl+d> to terminate>

2. Example :  cat > a4.txt

17. To append the contents of one file to another.
    1. Syntax :  cat <file 1> >> <file 2>
    2. Example :  cat a1.txt >> a2.txt
18. To append more than one file.
    1. Syntax :  cat <file 1> <file 2> <file 3>…>> <destination file>
    2. Example :  cat a1.txt a2.txt a3.txt >> aa.txt
19. To link files. <Creates a link between two files. changes in file will reflect in the other file also>
    1. Syntax :  ln <file 1> <file 2>
    2. Example : ln a1.txt a2.txt
20. To link 5 files.
    1. Syntax :  ln <source directory> <destination directory>
    2. Example : ln /home/anu/IT/* /home/anu/IT/
21. To sort files in alphabetical order / Display the file contents in descending / ascending order.
    1. Syntax :  sort <file>   // ascending order
    2. Example :  sort a1.txt
    3. Syntax : sort –r <file>   // descending order
    4. Example :  sort –r a1.txt
22. To list the contents of a directory.
    1. Syntax :  ls
23. To list all directories of a user.
    1. Syntax :  ls –l | egrep ‘^d’
24. To list only files from a directory.
    1. Syntax :  ls –l | egrep –v ‘^d’
25. To list hidden directories.
    1. Syntax :  ls -a
26. To display all files, subdirectories and files in the subdirectories including their sizes.
    1. Syntax :  ls -lR
27. To list only the subdirectories available in the present working directory.
    1. Syntax :  ls –lR | egrep –v ‘^d’
28. To list all directories / files that start with a specific character.
    1. Syntax :  ls <character>*
    2. Example : la a*
29. To list all files in current directory whose 2^ndcharacter is a digit.
    1. Syntax :  ls ?[0–9]*
30. To list files and directories recursively on a single line.
    1. Syntax :  ls –LR
31. To list all files which has dot at the end
    1. Syntax :  ls *.
32. To list all filenames which has a specific extension
    1. Syntax :  ls *.<extension>
    2. Example : ls *.txt
33. To list the file attributes and file size.
    1. Syntax :  ls -l
34. To change the file to read only mode. / to change the permission of a file
    1. Syntax :  chmod u-wx <file>

chmod g-wx <file>

chmod o-wx <file>

2. Example :  chmod u-wx a1.txt

chmod g-wx a1.txt 

chmod o-wx a1.txt

35. To view one page of a file.
    1. Syntax :  ls –l | more
36. To view the files page by page.
    1. Syntax :  ls –l | more

<press space bar to view next page> 

37. To view first 10 lines of a file / to display the beginning of a file
    1. Syntax :  head <file>
    2. Example :  head a1.txt
38. To view last 10 lines of a file / to display the end of a  file
    1. Syntax :  tail <file>
    2. Example :  tail a1.txt
39. To display only the first two characters of all lines from a file.
    1. Syntax :  cut –c1–2 <file name>
    2. Example :  cut –c1–2 aa.txt
40. To combine two files.
    1. Syntax :  cat <file 1> <file 2> > <new file 3>
    2. Example :  cat a1.txt a2.txt > a3.txt
41. To combine two files without duplicates.
    1. Syntax :  cat <file 1> <file 2> | sort –u > <new file 3>
    2. Example :  cat a1.txt a2.txt | sort –u > a3.txt
42. To add “;” to the end of the file.
    1. Syntax :  <cat <file>; echo “;”> > <new file>
    2. Example :  <cat a1.txt; echo “;”> > a5.txt
43. To delete the 7th line of a file.
    1. Syntax :  sed ‘<line number>d’ <file>
    2. Example :  sed ‘7d’ a1.txt
44. To split a file into smaller number of files with 3 lines in each file.
    1. Syntax :  split –l <number of lines> <file>
    2. Example :  split –l 3 aa.txt
45. To convert lowercase to uppercase.
    1. Syntax :  cat <file> | awk ‘{print toupper<$0>}’
    2. Example :  cat aa.txt | awk ‘{print toupper<$0>}’
46. To convert uppercase to lowercase.
    1. Syntax :  cat <file> | awk ‘{print toupper<$0>}’
    2. Example :  cat aa.txt | awk ‘{print tolower<$0>}’
47. To combine two strings.
    1. Syntax :  echo <string1><string2>
    2. Example :  echo “IRTT” “CIVIL”
48. To count the number of words in a file.
    1. Syntax :  wc –w <file>
    2. Example :  wc –w aa.txt
49. To count the number of lines in a file.
    1. Syntax :  wc –l <file>
    2. Example :  wc –l aa.txt
50. To count the number of characters in a file.
    1. Syntax :  wc –m <file>
    2. Example : wc –m aa.txt
51. To search for a specific word in a file.
    1. Syntax :  grep <word> <file>
    2. Example :  grep civil aa.txt
52. To count the number of occurrence of a character in a file.
    1. Syntax :  grep –c <word> <file>
    2. Example :  grep –c civil aa.txt
53. To search for a specific file in a directory.
    1. Syntax :  find <present working directory> –type f –name <file>
    2. Example :  find /home/anu –type f –name aa.txt
54. To translate the character “I” in a file to “E”.
    1. Syntax :  cat <file> | tr <original character> <replace character>
    2. Example :  cat aa.txt | tr I E
55. To change the password.
    1. Syntax : passwd
56. To view the commands which was executed
    1. Syntax :  history
57. Show manual for a command
    1. Syntax :  man <command>
    2. Example :  man cat
58. To clear the screen.
    1. Syntax :  clear
59. To print todays date and calendar of the current month using a single command.
    1. Syntax :  cal
60. To print the calendar for year 2013
    1. Syntax :  cal <year>
    2. Example :  cal 2013
61. To print the calendar for 2012 for the month of March.
    1. Syntax :  cal <month> <year>
    2. Example :  cal 3 2012
62. To print date and time.
    1. Syntax :  date
63. Display user name.
    1. Syntax :  whoami
64. To find out who is logged in. / To print who is using the system presently.
    1. Syntax :  who
65. Display users full detail, user-id and group-id.
    1. Syntax :  id

 

 

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