FOSS@Exp2

00:04 | Posted by b.phanikrishna |

  1. Log into the system
  2. Use the ‘cat’ command to create a file containing the following data. Call it mytable use tabs to separate the fields.
1425    ravi      15.65
4320    ramu    26.27
6830    sita       36.15
1450    raju      21.86
  1. Use the cat command to display the file, mytable.
  2. Use the ‘vi’ command to correct any errors in the file, mytable.
  3. Use the ‘sort’ command to sort the file my table according to the first field. Call the sorted file my table (same name)
  4. Print the file mytable.
  5. Use the cut and paste commands to swap fields 2 and 3 of mytable. Call it my table (Same name)
  6. Print the new, my table.
  7. Logout of the system
  
  1. Log into the system
When we return on the system one screen will appear. In this we have to type 100.0.0.9 then we enter into editor. It asks our details such as
         Login : krishnasai
         password:
Then we get log into the commands.

  1. Use the cat command to create a file containing the following data. Call it mytable use tabs to separate the fields.
1425   Ravi     15.65
4320   Ramu   26.27
6830   Sita      36.15
1450   Raju     21.86
cat > mytable
1425   Ravi     15.65
4320   Ramu   26.27
6830   Sita      36.15
            1450   Raju     21.86
To save the file press Ctrl + D or Ctrl+Z
Description:-
Cat Command can view the file data and create a new file and also concatenate file
ü  Creating file
Cat>file1.txt
ü  Creating one file from several files
cat file1 file2 file3 > file4
This command combines the contents of the first three files into file4. With this command, file4 is created if it didn't already exist. (Or, it will overwrite file4 if file4 already existed.)
ü  Showing line numbers
cat -n myfile.txt
cat myfile -b
This prints the line number before each line that is output
ü  appending one file to another file
cat file1>>file2
Append file1 at the end of the file2

  1. Use the cat command to display the file, mytable.
$cat mytable
1425  Ravi  15.65
4320  Ramu  26.27
6830  Sita  36.15
1450  Raju  21.86



  1. Use the vi command to correct any errors in the file ,mytable
By using vi editor we have to correct errors occurred in creating file .
Open the file in vi editor as
Syntax: Vi mytable
Use vi command to correct errors


  1. Use the sort command to sort the file mytable according to the first field. Call the sorted file my table
$sort +1 mytable > mytable
Or
$ sort  -k 1  mytable > sortfile;cp sortfile mytable
Description:-
Sort:- is a simple and very useful command which will rearrange the lines in a text file so that they are sorted, numerically and alphabetically.
Syntax:  sort [OPTION]... [FILE]...
Options
Ø  -b, --ignore-leading-blanks      Ignore leading blanks.
Ø  -d, --dictionary-order  Consider only blanks and alphanumeric characters.
Ø-f, --ignore-case           Fold lower case to upper case characters.
Ø  -g, --general-numeric-sort        Compare according to general numerical value.
Ø  -i, --ignore-nonprinting            Consider only printable characters.
Ø  -M, --month-sort         Compare (unknown) < `JAN' < ... < `DEC'.
Ø  -h, --human-numeric-sort        Compare human readable numbers (e.g., "2K", "1G").
Ø  -n, --numeric-sort        Compare according to string numerical value.
Ø  -R, --random-sort        Sort by random hash of keys.
Ø  --random-source=FILE           Get random bytes from FILE.
Ø  -r, --reverse      Reverse the result of comparisons.
Ø  --sort=WORD Sort according to WORD: general-numeric -g, human-numeric -h, month -M, numeric -n, random -R, version -V.
Ø  -V, --version-sort         Natural sort of (version) numbers within text.
Note that this command does not actually change the input file, data.txt. If you want to write the output to a new file, output.txt, redirect the output like this:

sort data.txt > output.txt

You can perform a reverse-order sort using the -r flag. For example, the following command:
sort -r data.txt



  1. Print the file mytable
cat mytable
1425  Ravi   15.65
1450  Raju   21.86
4320  Ramu   26.27
6830  Sita       36.15

  1. Use the cut and paste commands to swap fields 2 and 3 of mytable. Call it my table (same name)
$cut -f1 > mytab1
$ cut –f 2 > mytab 2
$cut –f 3 > my tab3
$paste mytab3 mytab2 > mytab4
$paste mytab1 mytab4 > mytable

Description:
Cut
Remove or "cut out" sections of each line of a file or files.
Syntax
cut OPTION... [FILE]...
Options
Ø  -b, --bytes=LIST         Select only the bytes from each line as specified in LIST. LIST specifies a byte, a set of bytes, or a range of bytes; see Specifying LIST below.
Ø  -c, --characters=LIST  Select only the characters from each line as specified in LIST. LIST specifies a character, a set of characters, or a range of characters; see Specifying LISTbelow.
Ø  -d, --delimiter=DELIM           use character DELIM instead of a tab for the field delimiter.
Ø  -f, --fields=LIST         select only these fields on each line; also print any line that contains no delimiter character, unless the -s option is specified. LIST specifies a field, a set of fields, or a range of fields; see Specifying LIST below.
Ø  -n         This option is ignored, but is included for compatibility reasons.
Ø  --complement  complement the set of selected bytes, characters or fields.
Ø  -s, --only-delimited     do not print lines not containing delimiters.
Ø  --output-delimiter=STRING   use STRING as the output delimiter string. The default is to use the input delimiter.
To "cut" only the third field of each line, use the command:
cut -f 3 data.txt

If instead you want to "cut" only the second-through-fourth field of each line, use the command:
cut -f 2-4 data.txt

If you want to "cut" only the first-through-second and fourth-through-fifth field of each line (omitting the third field), use the command:
cut -f 1-2,4-5 data.txt

If you want the third field and every field after it, omitting the first two fields. In this case, you could use the command:
cut -f 3- data.txt

Specifying a range with LIST also applies to cutting characters (-c) or bytes (-b) from a line. For example, to output only the third-through-twelfth character of every line ofdata.txt, use the command:
cut -c 3-12 data.txt

paste command:
The paste command displays the corresponding lines of multiple files side-by-side.
Syntax: paste [OPTION]... [FILE]...
Examples: paste file1.txt file2.txt
This command would display the contents of file1.txt and file2.txt, side-by-side, with the corresponding lines of each file separated by a tab.

$ cat file1
Linux
Unix
Solaris
HPUX
AIX

paste command with a single file:

 1. paste command without any options is as good as the cat command when operated on a single file.
$ paste file1
Linux
Unix
Solaris
HPUX
AIX

2. Join all lines in a file:
$ paste -s file1
Linux   Unix    Solaris HPUX    AIX
-s option of paste joins all the lines in a file. Since no delimiter is specified, default delimiter tab is used to separate the columns.

3. Join all lines using the comma delimiter:
$ paste -d, -s file1
Linux,Unix,Solaris,HPUX,AIX
-d option is used to specify the delimiter. Using this -d and -s combination, all the lines in the file get merged into a single line.

 4. Merge a file by pasting the data into 2 columns:
$ paste - - < file1
Linux   Unix
Solaris HPUX
AIX
The '-' reads a line from the standard input. Two '-' reads 2 lines and pastes them side by side.


5.Merge a file by pasting the data into 2 columns using a colon separator:
$ paste -d':' - - < file1
Linux:Unix
Solaris:HPUX
AIX:
        This is same as joining every 2 lines in a file.

6. Merge a file by pasting the file contents into 3 columns:
$ paste - - - < file1
Linux   Unix    Solaris
HPUX    AIX

7. Merge a file into 3 columns using 2 different delimiters:
$ paste -d ':,' - - - < file1
Linux:Unix,Solaris
HPUX:AIX,
The -d option can take multiple de-limiters. The 1st and 2nd columns is separated by ':', whereas the 2nd and 3rd are separated by a ','.


paste command examples for multiple files handling

 Let us consider a file, file2, with the following contents:
$ cat file2
Suse
Fedora
CentOS
OEL
Ubuntu


8. paste contents of 2 files side by side.
$ paste file1 file2
Linux   Suse
Unix    Fedora
Solaris CentOS
HPUX    OEL
AIX     Ubuntu
paste command is used in scenarios to merge multiple files side by side. As shown above, the file contents are pasted side by side.

 9. paste contents of 2 files side by side with a comma separator:
$ paste -d, file1 file2
Linux,Suse
Unix,Fedora
Solaris,CentOS
HPUX,OEL
AIX,Ubuntu


10. paste command can take standard input in case of multiple files too:
$ cat file2 | paste -d, file1 -
Linux,Suse
Unix,Fedora
Solaris,CentOS
HPUX,OEL
AIX,Ubuntu

Like this as well:
$ cat file1 | paste -d, - file2
Linux,Suse
Unix,Fedora
Solaris,CentOS
HPUX,OEL
AIX,Ubuntu
One more:

$ cat file1 file2 | paste -d, - -
Linux,Unix
Solaris,HPUX
AIX,Suse
Fedora,CentOS
OEL,Ubuntu


11. Read lines in both the files alternatively:
$ paste -d'\n' file1 file2
Linux
Suse
Unix
Fedora
Solaris
CentOS
HPUX
OEL
AIX
Ubuntu


  1. Print the new file, mytable
cat mytable
1425   15.65   Ravi
1450   21.86   Raju
4320   26.27   Ramu
6830   36.15   Sita

  1. Logout the system.
Syntax: exit
Description: In our current directory press exit to log out from the commands



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