In general, calling cat with just one argument is a useless use of cat. Instead of running cat 3 times, just do:
That's a bit more optimized than your way.
Beyond that, no; there's no UNIX system call to insert data before other data in a file, and I don't know a system that does. Nor is there a faster form of read() than the general purpose one, why would anyone ever use the "slow" one?
If whatever's using these datafiles can accept input on stdin, you could generate them at runtime to avoid the extra reads and wasted storage:
Last edited by Corona688; 05-11-2010 at 02:11 PM..
I have a flat file and need to count no of records in the file less the header and the trailer record.
I would appreciate any and all asistance
Thanks
Hadi Lalani (2 Replies)
All,
I am new to unix and i have the following requirement.
I have file(s) landing into input directory with timestamp, first i want to copy all these files into seperate directory then i want to rename these files without timestamp and also remove header,trailer from that file..
Could... (35 Replies)
Hi All,
I am karthik. I am new to this forum. I have one requirement.
I have a file with header and footer.
Header may be like
HDR0001
or
FILE20090110
(Assume it is unknown so far, but i am sure there is a header in the file)
likewise file has the trailer too.
I just... (7 Replies)
How can we a shell script and pass date parameters .I have 3 files comming from Datastage with |" delimited
I need append 3 files as above: File1:
P0000|"47416954|"AU|"000|"INS|"0000|"|"20060601|"99991231|"|"|"|"|"01
File 2:... (2 Replies)
Hi,
I want to add the below Header to all the files in sequence File1,File2,File3...etc
"ABC,<number of chracter in the file>"
e,g - If File1 is as below
pqrstuvdt
abcdefgh
then I want to add the above header into it ,So that File1 becomes as below
ABC,17
pqrstuvdt
abcdefgh
... (9 Replies)
Hi All,
I am trying write a simple command using AWK and SED to this but without any success.
Here is what I am using:
head -1 test1.txt>test2.txt|sed '1d;$d' test1.txt|awk '{print substr($0,0,(length($0)-2))}' >>test2.txt|tail -1 test1.txt>>test2.txt
Input:
Header
1234567
abcdefgh... (2 Replies)
Hi,
I need a script that validates a file header/detail/trailer. File layout is:
Header - Rec_Type|File_name|File_Date
Detail - Rec_Type|field1|field2|field3...
Trailder - Rec_Type|File_name|File_Date|Record_count
Sample Data:
HDR|customer_data.dat|20120709... (7 Replies)
I need to split the file based on pattern from position 34-37 while retaining the header and trailer records in each individual split file
Also is it possible to output the TOM and PAT records in the same output file ?
I need the output file names same as xyz_pattern_Datetimestamp.txt
... (23 Replies)
I have a EBCDIC multi layout file which has a header record which is 21 bytes, The Detail records are 2427 bytes long and the trailer record is 9 bytes long.
Is there a command to remove the header as well as trailer record and read only the detail records while at the same time not altering... (1 Reply)
Discussion started by: abhilashnair
1 Replies
LEARN ABOUT NETBSD
cat
CAT(1) BSD General Commands Manual CAT(1)NAME
cat -- concatenate and print files
SYNOPSIS
cat [-beflnstuv] [-] [file ...]
DESCRIPTION
The cat utility reads files sequentially, writing them to the standard output. The file operands are processed in command line order. A
single dash represents the standard input, and may appear multiple times in the file list.
The word ``concatenate'' is just a verbose synonym for ``catenate''.
The options are as follows:
-b Implies the -n option but doesn't number blank lines.
-e Implies the -v option, and displays a dollar sign ('$') at the end of each line as well.
-f Only attempt to display regular files.
-l Set an exclusive advisory lock on the standard output file descriptor. This lock is set using fcntl(2) with the F_SETLKW command.
If the output file is already locked, cat will block until the lock is acquired.
-n Number the output lines, starting at 1.
-s Squeeze multiple adjacent empty lines, causing the output to be single spaced.
-t Implies the -v option, and displays tab characters as '^I' as well.
-u The -u option guarantees that the output is unbuffered.
-v Displays non-printing characters so they are visible. Control characters print as '^X' for control-X; the delete character (octal
0177) prints as '^?'. Non-ascii characters (with the high bit set) are printed as 'M-' (for meta) followed by the character for the
low 7 bits.
EXIT STATUS
The cat utility exits 0 on success, and >0 if an error occurs.
EXAMPLES
The command:
cat file1
will print the contents of file1 to the standard output.
The command:
cat file1 file2 > file3
will sequentially print the contents of file1 and file2 to the file file3, truncating file3 if it already exists. See the manual page for
your shell (i.e., sh(1)) for more information on redirection.
The command:
cat file1 - file2 - file3
will print the contents of file1, print data it receives from the standard input until it receives an EOF ('^D') character, print the con-
tents of file2, read and output contents of the standard input again, then finally output the contents of file3. Note that if the standard
input referred to a file, the second dash on the command-line would have no effect, since the entire contents of the file would have already
been read and printed by cat when it encountered the first '-' operand.
SEE ALSO head(1), hexdump(1), lpr(1), more(1), pr(1), tail(1), view(1), vis(1), fcntl(2)
Rob Pike, "UNIX Style, or cat -v Considered Harmful", USENIX Summer Conference Proceedings, 1983.
STANDARDS
The cat utility is expected to conform to the IEEE Std 1003.2-1992 (``POSIX.2'') specification.
The flags [-belnstv] are extensions to the specification.
HISTORY
A cat utility appeared in Version 1 AT&T UNIX. Dennis Ritchie designed and wrote the first man page. It appears to have been cat(1).
BUGS
Because of the shell language mechanism used to perform output redirection, the command ``cat file1 file2 > file1'' will cause the original
data in file1 to be destroyed! This is performed by the shell before cat is run.
BSD September 23, 2006 BSD