Visit Our UNIX and Linux User Community


How to delete N bytes from the starting of the file from a C function???


 
Thread Tools Search this Thread
Top Forums Programming How to delete N bytes from the starting of the file from a C function???
# 1  
Old 11-15-2007
How to delete N bytes from the starting of the file from a C function???

Hi,
I want to delete the initial few lines (or even bytes) from a file.
I want to do this from a C function & this is in Linux platform.
The truncate & ftruncate is allowing me to delete bytes from the end only.
Any linux C function calls or ideas or any suggestions??

I'm in a dead lock..Plz help

Wishes
Jay
# 2  
Old 11-15-2007
I even tried

lseek(fd, (off_t)numOfBytes, SEEK_SET);
i=ftruncate(fd,1000);

but this didn't help
# 3  
Old 11-15-2007
No, there is no function to delete from the middle of a file, only to truncate.

You have two options

(a) open one file, read buffer fulls and write earlier in the file until you get to the end then truncate

(b) open a new file, copy the data you want to keep to the new file and then close it and rename it onto the original.

Previous Thread | Next Thread
Test Your Knowledge in Computers #113
Difficulty: Easy
Linux is not Unix per se, but Linux is a Unix-like operating system.
True or False?

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

How to grep a line not starting with # from a file (there are two lines starting with # and normal)?

e.g. File name: File.txt cat File.txt Result: #INBOUND_QUEUE=FAQ1 INBOUND_QUEUE=FAQ2 I want to get the value for one which is not commented out. Thanks, (3 Replies)
Discussion started by: Tanu
3 Replies

2. 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

3. UNIX for Advanced & Expert Users

How to delete a* file with out deleting file name starting with a?

Hi, I have a query: I have a bunch of files starting letter with 'a' (example: abhi,all,anand,animal,a1.txt,allow.java,a*) here i want to delete/remove only a* folder but not other files and folders. and a* folder is present in so many other folders. what is unix command to delete... (9 Replies)
Discussion started by: rajanikanth86
9 Replies

4. 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

5. 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

6. Shell Programming and Scripting

Delete a line in a file starting with - Perl one-liner

Hi I need a perl onliner to delete a line in a file starting with few words. Example file.txt ---------- my name is don I live in London I am woking as engineer I want to delete a line starting with 'I live in' using perl oneliner and in place edit with out temporary files Thanks... (2 Replies)
Discussion started by: ammu
2 Replies

7. 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

8. Shell Programming and Scripting

How to delete initial N bytes from the starting of the file using sed?

I want to delete initial N bytes of a file using sed. How can I do that? (3 Replies)
Discussion started by: jockey007
3 Replies

9. Shell Programming and Scripting

Delete lines starting with XX or YY or ZZ or ....

Hi There! My final task for today is to delete lines starting with certain numbers for e.g., my text block is and i want to delete all lines starting with 11 or 17 or 21 I know i can use multiple sed commands like sed '/^11,/d' <filename> sed '/^17,/d' <filename> sed '/^21,/d'... (2 Replies)
Discussion started by: orno
2 Replies

10. Shell Programming and Scripting

delete bytes from file

I'm doing a bit of hex editing with dd and I can replace values fairly simply. However, I've run across a situation where I need to delete bytes in the file and I'm not sure how to do that. For example: Input file has: 1234567890 Output needs to be: 123abc90 I tried this: printf... (6 Replies)
Discussion started by: Loriel
6 Replies

Featured Tech Videos