Sponsored Content
Top Forums UNIX for Dummies Questions & Answers ConCATenating binaries but excluding last bytes from each file Post 302877652 by grolido on Monday 2nd of December 2013 06:49:02 PM
Old 12-02-2013
ConCATenating binaries but excluding last bytes from each file

Hi there, shameful Linux Newbie here Smilie

I was wondering if you could help with my problem...
I have plenty of files I'd like to concatenate. I know how to basically use cat command but that won't be enough from what I need : excluding the last xx bytes from files before assembling since there's some redundancy


the interesting part is the xx bytes to remove is determined by the filename themselves, ie


file 1 is named something like 0-54548
file 2 is named something like 54475-648459
file 3 is named 648345-1269494
etc


so for file 1 I would have to drop bytes between 54475 till the end before joining file 2. etc
it would be easier if it was always the exact same bytes value to remove , alas there are some variations, so it must be calculated from filenames.


I feel like it's possible to script something with not much lines within a loop, but my unix knowledge is way too rudimentary for now ^^


I also read about dd command which could probably be of some help to generate the files without the unwanted part, now I'm a bit clueless about extracting character chains from filenames, turning into numeric values, doing the maths and use this dd or whatever else command so I can assemble the resulting files...
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Take a file from the system and put on tape and reset the file to 0 bytes

:mad: I did this the other day but one of my support personnel removed my history so i could call it back up to remeber the exact command since i am air-headed at times. I am trying to take a 30 MEG file off the system and drop it to tape then i want to make the file go back to being 0 bytes so... (1 Reply)
Discussion started by: JackieRyan26
1 Replies

2. Shell Programming and Scripting

Remove first N bytes and last N bytes from a binary file on AIX.

Hi all, Does anybody know or guide me on how to remove the first N bytes and the last N bytes from a binary file? Is there any AWK or SED or any command that I can use to achieve this? Your help is greatly appreciated!! Best Regards, Naveen. (1 Reply)
Discussion started by: naveendronavall
1 Replies

3. Shell Programming and Scripting

Concatenating the two lines in a file

hi My requirement is i have a file with some records like this file name ::xyz a=1 b=100,200 ,300,400 ,500,600 c=700,800 d=900 i want to change my file a=1 b=100,200,300,400 c=700,800 d=900 if record starts with " , " that line should fallows the previous line.please give... (6 Replies)
Discussion started by: srivsn
6 Replies

4. UNIX for Dummies Questions & Answers

Bytes of character in file

Hi, How do I check for the total bytes of character used by a file? Can I used a od command to check? Thanks. (1 Reply)
Discussion started by: user50210
1 Replies

5. Programming

how to inspect the bytes in a file?

What is the easiest way to inspect the bytes stored in a file? Ideally, If my file was 10 bytes each of which had only the high bit set, I'd be able to browse for it and get output like this: 01 - 10000000 02 - 10000000 03 - 10000000 04 - 10000000 05 - 10000000 06 - 10000000 07 -... (7 Replies)
Discussion started by: sneakyimp
7 Replies

6. Shell Programming and Scripting

Error PHP Fatal error: Allowed memory size of 67108864 bytes exhausted(tried to allocate 401 bytes)

While running script I am getting an error like Few lines in data are not being processed. After googling it I came to know that adding such line would give some memory to it ini_set("memory_limit","64M"); my input file size is 1 GB. Is that memory limit is based on RAM we have on... (1 Reply)
Discussion started by: elamurugu
1 Replies

7. Programming

Copying 1024 bytes data in 3-bytes chunk

Hi, If I want to copy a 1024 byte data stream in to the target location in 3-bytes chunk, I guess I can use the following script. dd bs=1024 count=3 if=/src of=/dest But, I would like to know, how to do it via a C program. I have tried this with memcpy(), that did not help. (3 Replies)
Discussion started by: royalibrahim
3 Replies

8. UNIX for Dummies Questions & Answers

X bytes of 0, Y bytes of random data, Z bytes of 5, T bytes of 1. ??

Hello guys. I really hope someone will help me with this one.. So, I have to write this script who: - creates a file home/student/vmdisk of 10 mb - formats that file to ext3 - mounts that partition to /mnt/partition - creates a file /mnt/partition/data. In this file, there will... (1 Reply)
Discussion started by: razolo13
1 Replies

9. Shell Programming and Scripting

Shell script - entered input(1-40 bytes) needs to be converted exactly 40 bytes

hello, suppose, entered input is of 1-40 bytes, i need it to be converted to 40 bytes exactly. example: if i have entered my name anywhere between 1-40 i want it to be stored with 40 bytes exactly. enter your name: donald duck (this is of 11 bytes) expected is as below - display 11... (3 Replies)
Discussion started by: shravan.300
3 Replies

10. Shell Programming and Scripting

Get file's first x bytes

is there a better way to do this: head -c 10000k /var/dump.log | head -c 6000k unfortunately, the "-c" option is not available on sun solaris. so i'm looking at "dd". but i dont know how to use it to achieve the same exact goal as the above head command. this needs to work on both solaris... (5 Replies)
Discussion started by: SkySmart
5 Replies
cat(1)								   User Commands							    cat(1)

NAME
cat - concatenate and display files SYNOPSIS
cat [-nbsuvet] [file...] DESCRIPTION
The cat utility reads each file in sequence and writes it on the standard output. Thus: example% cat file prints file on your terminal, and: example% cat file1 file2 >file3 concatenates file1 and file2, and writes the results in file3. If no input file is given, cat reads from the standard input file. OPTIONS
The following options are supported: -n Precede each line output with its line number. -b Number the lines, as -n, but omit the line numbers from blank lines. -u The output is not buffered. (The default is buffered output.) -s cat is silent about non-existent files. -v Non-printing characters (with the exception of tabs, new-lines and form-feeds) are printed visibly. ASCII control characters (octal 000 - 037) are printed as ^n, where n is the corresponding ASCII character in the range octal 100 - 137 (@, A, B, C, . . ., X, Y, Z, [, , ], ^, and _); the DEL character (octal 0177) is printed ^?. Other non-printable characters are printed as M-x, where x is the ASCII character specified by the low-order seven bits. When used with the -v option, the following options may be used: -e A $ character will be printed at the end of each line (prior to the new-line). -t Tabs will be printed as ^I's and formfeeds to be printed as ^L's. The -e and -t options are ignored if the -v option is not specified. OPERANDS
The following operand is supported: file A path name of an input file. If no file is specified, the standard input is used. If file is `-', cat will read from the standard input at that point in the sequence. cat will not close and reopen standard input when it is referenced in this way, but will accept multiple occurrences of `-' as file. USAGE
See largefile(5) for the description of the behavior of cat when encountering files greater than or equal to 2 Gbyte ( 2**31 bytes). EXAMPLES
Example 1: Concatenating a file The following command: example% cat myfile writes the contents of the file myfile to standard output. Example 2: Concatenating two files into one The following command: example% cat doc1 doc2 > doc.all concatenates the files doc1 and doc2 and writes the result to doc.all. Example 3: Concatenating two arbitrary pieces of input with a single invocation The command: example% cat start - middle - end > file when standard input is a terminal, gets two arbitrary pieces of input from the terminal with a single invocation of cat. Note, however, that if standard input is a regular file, this would be equivalent to the command: cat start - middle /dev/null end > file because the entire contents of the file would be consumed by cat the first time `-' was used as a file operand and an end-of-file condition would be detected immediately when `-' was referenced the second time. ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables that affect the execution of cat: LANG, LC_ALL, LC_CTYPE, LC_MES- SAGES, and NLSPATH. EXIT STATUS
The following exit values are returned: 0 All input files were output successfully. >0 An error occurred. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ |CSI |enabled | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ SEE ALSO
touch(1), attributes(5), environ(5), largefile(5), standards(5) NOTES
Redirecting the output of cat onto one of the files being read will cause the loss of the data originally in the file being read. For exam- ple, example% cat filename1 filename2 >filename1 causes the original data in filename1 to be lost. SunOS 5.10 1 Feb 1995 cat(1)
All times are GMT -4. The time now is 04:53 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy