does head create new file


 
Thread Tools Search this Thread
Top Forums UNIX for Advanced & Expert Users does head create new file
# 1  
Old 09-15-2009
does head create new file

hi,

Here my doubt is can we create a file using head/tail command in unix.

for example: my file consists 2000 lines , i want to cut it into 2. does this work please give correct command line.

head -1000 abc.txt > acd.txt
tail -1000 abc.txt > bdc.txt

hi,

Here my doubt is can we create a file using head/tail command in unix.

for example: my file consists 2000 lines , i want to cut it into 2. does this work please give correct command line.

head -1000 abc.txt > acd.txt
tail -1000 abc.txt > bdc.txt

Last edited by vbe; 09-15-2009 at 05:23 AM.. Reason: "threadjacking"
# 2  
Old 09-15-2009
1. Yes the command you had given will work correctly.
That is
1-1000 lines
bcd.txt
1000-2000 lines

Why you have doubt in that, you could have executed and checked by yourself ?

2. If you are checking for the other ways.. try split command.

3. Why you posted this here ? You should create a new post ?!
# 3  
Old 09-15-2009
That's easy to test:
Code:
perl -e 'for($i=0;$i<26;$i++){print chr(ord('A')+$i)x40,"\n";}' > test1.txt
head -13 test1.txt > part1.txt
tail -13 test1.txt > part2.txt

Do you now have 2 files, part1.txt and part2.txt, one containing lines A-M, the other containing lines N-Z?
# 4  
Old 09-15-2009
Most versions of "tail" have a limited buffer. Mine is 20k. See "man tail" for your system. Thus the "tail -count" syntax is not reliable where the volume of output will exceed the size of the buffer - in fact it will just give you as many lines as it can.

Code:
Here is an example of "tail" going wrong on one of my logs:

tail -200 mylog|wc -l
200

ukh44004 # tail -300 mylog|wc -l
218

tail -400 mylog|wc -l
218


The unix "split" command mentioned earlier will give the correct result for simple text files.
# 5  
Old 09-15-2009
Hi Chitishri,
Code:
head -1000 abc.txt               _______this will give you the first 1000 lines
tail -1000 abc.txt                 ________this will give the last 1000 lines

so (> acd.txt) which yu added to the above command wil just create a file or override to the existed file .

note:like if you write cat file >new_file _______________here same thing happens. 

not the head command will create file.

regards,
Sanjay.
# 6  
Old 09-15-2009
This is safer than "head" and "tail" for large numbers of lines:

Code:
sed -n '1,1000 p' abc.txt > acd.txt
sed -n '1001,$ p' abc.txt > bcd.txt

Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Rsync whole folder and head of each file

Hello, I am trying to backup the whole folder which contains years of data and huge size, some files are > 10GB. I want keep the exact organization of the folder, except that for bigger file only part of it (say head -50, or simply only the name of the file) will be kept. Then the structure of the... (2 Replies)
Discussion started by: yifangt
2 Replies

2. Shell Programming and Scripting

How can i get the head of file while using awk?

Hi All, I'm a newbie here, I'm just wondering how can i get the head of my file while using awk? input data: nik1,nik2,nik3 nik2,nik3,nik4 nik3,nik4,nik5 expected output is: nik1 because it is in the top and it is in the first delimeted. i tried awk -F "," '{print $1}' but i... (2 Replies)
Discussion started by: nikki1200
2 Replies

3. Shell Programming and Scripting

appending the count of line in each file at head of each file

hello everybody, I have some files in directory.each file contain some data. my requirement is add the count of each line of file in head of each file. any advice !!!!!!!! (4 Replies)
Discussion started by: abhigrkist
4 Replies

4. Shell Programming and Scripting

Help awking a 'head -1 file.txt' input

Hi there, my ksh script collects a procstack trace for a particular pid and then greps it by a transaction id to find out the pthread ID: ---------- tid# 1876087 (pthread ID: 4466) ---------- So the pthread ID I want is 4466 in this case, and it is assighed to the variable $pthread.... (4 Replies)
Discussion started by: tmf33uk
4 Replies

5. Shell Programming and Scripting

Add one text line in the head of the file

hello, how can I add one text line string at the line number one of a file. thankx, (5 Replies)
Discussion started by: Ahmed waheed
5 Replies

6. Shell Programming and Scripting

head command with more than one file

Hi, I have the following problem. I have files with one column of data (let's say file1.dat, file2.dat...file6.dat), and I would like to record the first value of the column of each file into another file (let's name it fileall.dat), which would have the the six values, one in each column. I use to... (4 Replies)
Discussion started by: josegr
4 Replies

7. Programming

which head file define '_IO_*'

Under Solaris 10,I compile following file, #include <sys/types.h> #include <sys/stat.h> #include <sys/termios.h> #include <sys/ioctl.h> #include <stdio.h> #include <stdlib.h> #include <stddef.h> #include <string.h> #include <unistd.h> #include <signal.h> #define _IO_UNBUFFERED __SNBF... (1 Reply)
Discussion started by: konvalo
1 Replies

8. Shell Programming and Scripting

printing first n lines in a file without using head

i have to print first n lines of a file. how can i do that without using head command. for some reason i do not want to use Head. is there a way to get that result using awk or sed?. i an using this on korn shell for AIX Thanks.. (7 Replies)
Discussion started by: dareman123
7 Replies

9. UNIX for Dummies Questions & Answers

how to save to file as head rows_numbers big_file

hi all, Please help me to write. How to create the file by getting numbers of rows from orginal file. I tried the following one, doesn't work. head 50000 file1 >> file1_1 head: cannot open `50000' for reading: No such file or directory Thank you (2 Replies)
Discussion started by: mr_bold
2 Replies

10. UNIX for Dummies Questions & Answers

head command wont work on MF file

I am trying to do a head on a mainframe file and on doing ti just gives me a blank screen with nothing on it. however, when i do a tail for the same file...i get a few lines on the screen. i know tht mainframe files have all the records on one line...does this have to do something with this.... (10 Replies)
Discussion started by: alfredo123
10 Replies
Login or Register to Ask a Question