Shell Programming and Scripting

Hi

i am writing a cron job. in this script i need to delete some line which is match with some pattern.
following code i written for deletion

Code:

sed '1,'$Max_LIneNo' d' myfile.txt >tempfile.tmp
mv tempfile.tmp myfile.txt

this command is working fine but the problem is that after this deletion every time will give the rights to myfile.txt.

is there any other way to perform this deletion without help of any temp file

one more point i need to delete lines permanetly from file.

thanx in advance

If you have GNU sed, then could use the below option which makes the change/writes to the original input file.

Code:

sed -i '1,'$Max_LIneNo' d' myfile.txt

it is not working

showed error msg

Code:

sed :illegal option  --i is not valid

Can't you just set a proper umask before executing the commands (man umask).

sorry i did not get you.

now what should i do for unmask the command?

umask, not unmask. What does

Code:

ls -l  myfile.txt

give, before and after?