Large file data handling issue


 
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# 8  
Yes, I do mean whether the file contains unix standard line terminators (line feed characters) to define records or whether it is just a "stream". None of the unix standard utilities such as "sed" and "awk" are designed to deal with files which have no definded record format.
# 9  
How can I overcome this limitation
# 10  
Can use you post the last bytes of the file from the output of the 'od' command:
Code:
od -c filename

# 11  
2225460 1 2 - 1 0 - 2 5 0 8 : 4 9 : 0
2225500 3 |
2225502
# 12  
You can cheat by telling awk that | is the record separator. It won't try to process all 600K as one line.

Note this reads the file twice, so that doublethink isn't necessary to figure out what the last 'line' is.

Code:
awk -v RS="|" 'NR==FNR { LAST=NR; next } FNR!=LAST { printf("%s%s", P, $0); P="|" } END { printf("\n"); }' inputfile inputfile


Last edited by Corona688; 11-15-2012 at 12:11 PM..
# 13  
So the file has no line feed, you just want to get rid of the last byte. If you have gnu "head" you can do
Code:
head -c size-1 inputfile > outputfile

Or you can use dd to truncate the file in place (make backup if you need):
Code:
dd if=/dev/null of=inputfile bs=1 count=1 seek=size-1

Of course dd can do "head -c" too:
Code:
dd if=inputfile of=outputfile bs=size-1 count=1

If your input had line feed, you could truncate to size-2 and then append a line feed to it.
# 14  
If you haven't got a solution yet, Try this:
Code:
# Covert all '|' to new lines
sed 's/|/\n/' filename > temp_file
# Determine record number of last line(s) you want to drop
wc -l temp_file
less -n temp_file
# Convert new lines back to '|', xxxx is the last record you want to keep
head -xxxx temp_file | sed 's/\n/|/' > new_file

 

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