Shell Programming and Scripting

Dear All,

Is there a way to cut the lines that have been "head"

Here is what i m trying to do Please advice

there is file name dummy.txt

now i am trying to head this file 4 time by using a loop and every time this file is head with different values

e.g in first instance it will be head -1 for second interval it will be head -20 and so on.

these intevaral are random and are been generated by a counter evertime a script is executed counter bounce with a new value and according to that value file will be "head" four times.

Now the issue is, during the first interval if file is "head 5" times (i.e. head -5) output must be saved with a new file extension, and when its executed second time for (head -10) file should start from (6th value to 16th value and not from 1st to 10th) and so on.

please advice from this point..

Thankz in advance

Simple way to do it:

Code:

 
head -10 <file_name> | tail -5

what this peice of code is trying to do is: get top ten lines of the file and print last five of those to STD output. you can keep appropriate counters to iterate the loop. Also redirect to file accordingly.

thnkz for the reply.

the values mentioned here are just an example.

May be this can help you out..

here it is what i am trying to to

For e.g a file name dummy.txt contains value 1-10 coloum wise.

now i want to head this file 4 four times but with different interval (random numbers are generating from a counter.. no help needed for this case)

like in first instant file is head 2 times (head -2 <filename> [output will be 1 2]

now for second time when the file is head let say 4 times (i.e head -4 ) than output should be (3 4 5 6) and not (1 2 3 4).

Similarly, for third and fourth time.

May be this will help ya understand in a better way.

Please help

Thankz in advance.

ok, if I get it right try this:

Code:

sed -n '2,6p' <file_name>

this will print lines starting at column 2 to 6.

Substitute 2 & 6 with your loop variables.

let me know if you need more on this.

thankz a million shubhendu

now please help in one more thing

my files also contains spaces:

1

2

3

4

.
.
.

if want to remove these spaces how can i do this.

as the below mentioned command is also counting spaces.

You welcome.

This code will delete blank lines from the file:

Code:

 
sed '/^ *$/d' <file_name>

you can either PIPE this or redirect this to a tmp file and do next operation accordingly.

cheers.

simply awesome bro...

thnkz a million

GOD BLess ya

-----Post Update-----

Dear All,

now m stuck into this

the following command do execute and provide me my desired result

sed -n '2,6p' <file_name>

but now the issue is, if i want that the values are automatically palced in the said file how to do that

like

sed -n '$varaible1,$variable2p' <file_name>

where variable1 and variable2 are the values that will be placed randomly by the script [I have no issue of placing these variable] the only issue is with the command

please help

-----Post Update-----

please help