head is a program on Unix and Unix-like systems used to display the beginning of a text file or piped data.

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tail/head all line except X last/first Lines

for example i have this file : cat myfile 1 2 3 4 5 i want to print all lines except first 2 line . output should be like this : tail -n $(( $(wc -l myfile | awk '{print $1}') - 2 )) myfile 3 4 5 ...
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1answer
60 views

How to echo only 1st line from 'curl' command output?

I'm trying to get only first line of the curl command output. (Sorry if this is confusing) Let's say, for an instance, i run simply: # curl http://localhost <!-- This is the hidden line i want to ...
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27 views

Read binary file of expected size blocking until the size is equals expected

I want to read a dowloaded file while it is being written for instance with tail -f -c +1 $filename and to redirect it to another tool (which decodes it) with a pipe |. This works fine but I am doing ...
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16 views

remove last n lines of command line output? [duplicate]

When I run cat duplicates.txt I get the entire contents of the file duplicates.txt. The end of the file appears right above my command prompt. I can conveniently copy and paste content from it to my ...
3
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1answer
113 views

Head on very large files

I have 2 very big files (27G and 40G), which are output of dd command on a failing hard drive. I wanted to compare the first bytes to see if the 27G bytes is the begining/substring of the 40G. I ...
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1answer
134 views

How to grep for line numbers in a binary file?

I'm on Centos 5 Linux and using GNU grep v2.5.1 and looking at a 36GB log file. It is huge and I need to find around a million lines starting from the occurrence of a string 6307459 in the log file ...
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1answer
52 views

Head waits for full stdin before printing

When one runs ls | head head seems to wait for the full output of the piped command before printing to screen. This is undesirable when the command will take a very long time to run, such as when ...
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154 views

Copy huge file skipping first line using dd in Linux

I was trying to copy the content of a huge file (10GB) to another skipping the first line (as in head -n1). I tried multiple ways of head, tail, awk and sed. Settled on using tail -n+2 > ./xab.1 ...
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3answers
3k views

Creating a large file of random bytes quickly

I want to create a large file ~10G filled with zeros and random values. I have tried using: dd if=/dev/urandom of=10Gfile bs=5G count=10 it creates a file of about 2Gb and exits with a exit status ...
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1answer
25 views

Using head to see up to a character

I have some C source files and a lot of them have a single, 1-line comment at the top that offers a short description of what that program does (I haven't done anything complex enough to warrant a ...
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1answer
134 views

Extracting part of a large SQL dump

Is there a way to chain commands like grep and head together to extract a portion of a file? The problem is that somewhere in my .sql file I have an old data that I need to compare to new data and I ...
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1answer
344 views

head and cat don't recognize Microsoft Excel text files

I have a large .xls file with 53760 rows and 19 columns. I saved it as Tab Delimited Text in order to pre-process it through command line tools and load it into R later. However, when I run head ...
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1answer
260 views

How to resolve conflicts when two binaries have the same name

Running OS X (10.9), I have a program called 'HEAD' in /Applications/XAMPP/xamppfiles/bin/, which is related to libwww-perl. The OS also has an unrelated program called 'head' in /usr/bin/ Since the ...
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1answer
334 views

head hangs or doesn't terminate on Linux

I'm using, (uname -a says) Linux ip-x-x-x-x 2.6.21.7-2.fc8xen-ec2-v1.0 #1 SMP Tue Sep 1 10:25:30 EDT 2009 x86_64 GNU/Linux. I've got a script, foo.sh with 100 lines of code and when I run head ...
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1answer
5k views

How to easily break up a text file into pieces smaller than a threshold?

I have some text files that are 100 to 300 MB in length that I want to view in Emacs, but my Emacs gets into some performance issues opening and traversing such large files. Therefore, I'm looking ...
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3answers
2k views

zcat | head : write error from large gz file

I was trying zcat to get only the first 1M lines of a compressed .gzip file into a new one. However, I get the following error: $ zcat path/to/R2.fq.gz | head -100 >R2.fqtest head: write error: ...
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3answers
12k views

Opposite of tail: all lines except the last n lines

How can I discard the last n lines of a file with a unix command line filter? That would be sort of the opposite of tail: tail discards the first n lines but pipes the rest through, but I want the ...
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1answer
73 views

What's the best way to view lines X through Y of a large file?

I have a very large text file and I want to view, say, lines 2000 through 2010 (with the line numbers included) I know one sort of roundabout way of getting there: sc -l [file] cat -n [file] | tail ...
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1answer
941 views

Unix tool to output first n characters in an UTF-8 encoded file

I want to print the first 1000 characters in an UTF-8 encoded file. I know that the head tool can print the first n bytes of a file, but it may cut a character in the middle so that I get garbled ...
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3answers
5k views

Using 'head' or 'tail' on HUGE text file - 19 GB

I have a problem with viewing chunks of a very large text file. This file, approximately 19 GB, is obviously too big to view by any traditional means. I have tried head 1 and tail 1 (head -n 1 ...
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1answer
1k views

How to solve “Broken Pipe” error when using awk with head

I'm getting broken pipe errors from a command that does something like: ls -tr1 /a/path | awk -F '\n' -vpath=/prepend/path/ '{print path$1}' | head -n 50 Essentially I want to list (with absolute ...
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2answers
159 views

How to copy head of files to another folder, keeping tree structure?

I have a bunch of huge files (4GB+ each) with the same extension in a directory structure in a network drive, but am only interested in the first few bytes of each, so I'd like to copy them all to my ...
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2answers
2k views

Stopping after first line of output

I try to do the following in a Bash script: run a command (such as tail -f log_file), wait until a specific output arrives, then stop the command, and go on with the script. I tried the following, ...
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3answers
806 views

How to grab a random section in the middle of a huge file?

I have a huge log file of around 3.5 GB and would like to sample random sections in the middle of say 10 MB for the purpose of debugging what my application is doing. I could use head or tail ...