This is our old Q&A Site. Please post any new questions and answers at

Hello , i need to write a command where tcp dump makes a capture of size 7GB, i tried -C 7168m but i got "invalid file size" error, does this command have a size limitation? and is there a way to solve this problem keeping the captures in 1 file ?

asked 14 Jul '15, 05:32

yas1234's gravatar image

accept rate: 0%

edited 15 Jul '15, 08:36

From the tcpdump man page:

-C file_size = Before writing a raw packet to a savefile, check whether the file is currently larger than file_size and, if so, close the current savefile and open a new one. Savefiles after the first savefile will have the name specified with the -w flag, with a number after it, starting at 1 and continuing upward. The units of file_size are millions of bytes (1,000,000 bytes, not 1,048,576 bytes).

-W = Used in conjunction with the -C option, this will limit the number of files created to the specified number, and begin overwriting files from the beginning, thus creating a 'rotating' buffer. In addition, it will name the files with enough leading 0s to support the maximum number of files, allowing them to sort correctly. Used in conjunction with the -G option, this will limit the number of rotated dump files that get created, exiting with status 0 when reaching the limit. If used with -C as well, the behavior will result in cyclical files per timeslice.

permanent link

answered 14 Jul '15, 06:17

Amato_C's gravatar image

accept rate: 14%

What do you mean by "in conjunction"? Do you want to merge the separate files into one large file?

(14 Jul '15, 06:22) Amato_C
Your answer
toggle preview

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here



Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text]( "title")
  • image?![alt text](/path/img.jpg "title")
  • numbered list: 1. Foo 2. Bar
  • to add a line break simply add two spaces to where you would like the new line to be.
  • basic HTML tags are also supported

Question tags:


question asked: 14 Jul '15, 05:32

question was seen: 18,013 times

last updated: 15 Jul '15, 08:36

p​o​w​e​r​e​d by O​S​Q​A