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Top Forums Shell Programming and Scripting Overwrite & Delete in Text File Post 302131842 by 33junaid on Tuesday 14th of August 2007 03:01:32 AM
Old 08-14-2007
Overwrite & Delete in Text File

Dear All,

I have text file like this:

Header
Record 1
Record 2
.......
Record n
Tail

This line of code :
awk '{ if ( NR == 1 ) { head=substr($0,1,300);} else { last = substr($0,1,300);}END{printf "Header is : %-300s Trailer is : %-300s\n", head, last}' filename

converted Header and Trailer in one line and within 300 character each.The output is just one line.

Now I want to overwrite this one line above (Header+ Tail) over the first line of original file (orginal header) and delete the Tail........i can copy this header and tail to new file and then append Record 1 to Record n to this new file, but that will cause too low performance........so I think better to update first and the last line of the this file.................so how can i do that?

i.e. 1-update the header with new line i.e. (header+trailer)
2-delete the tail in original file (may be using cut tail -1 filename?)
 

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cddrec(1)						      General Commands Manual							 cddrec(1)

NAME
cddrec - Read Directory Record from CD-ROM directory SYNOPSIS
/usr/bin/cddrec [-s number] [-b] file OPTIONS
Specifies the File Section for which the Directory Record is to be read. The numbering starts with one and can be any whole number. If this option is not used, the last file section of the named file is assumed. Copies the entire Directory Record from a CD-ROM in binary format to standard output. Names a file within the CD-ROM file hierarchy of a mounted CD-ROM File System. DESCRIPTION
The cddrec command reads the Directory Record associated with a file or directory on a mounted CD-ROM and lists its contents on standard output. The output is formatted in a table that contains the name of each field of the Directory Record and the corresponding contents of the entry as recorded on the CD-ROM. Note that the System Use field is not listed because it may contain non-printable characters. Users must have read permission for file in order to execute the command. EXIT STATUS
The following exit values are returned: The command was successful. The named file was not found, or was not within the CD-ROM hierarchy, or access permission was denied. The File Section indicated by file does not exist. SEE ALSO
Functions: cd_cdrec(3), cd_drec(3) cddrec(1)
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