[..]
I haven't tried a performance comparison, but the following uses fewer processes and pushes less data through the pipes so it could be faster. [..]
The number of processes between the various non-find solutions does not differ much, but I never realized that the amount of data through the pipes could matter that much. Thank you for that insight..
I did some tests with 10.000 input file and it was up to a factor 5 when selection is done before the pipe (obviously depending on the amount of data that can be saved by selecting before the pipe)..
--
My system does not have a lot of line length limitations , so I was able to use this script (since the header and footer do not matter):
Which is a little bit faster still, since it doesn't even use a pipe..
I have 2 files pipe delimted and want to merge them based on a key
e.g file 1
123$aaa$yyy$zzz
345$xab$yzy$zyz
456$sss$ttt$foo
799$aaa$ggg$dee
file 2
123$hhh
345$ddd
456$xxx
888$zzz
so if the key is the first field, and the result should be the common key between file 1 and 2 (6 Replies)
Help in writing a script using sed which updates fileOne with the contents from fileTwo
Example:
Contents of fileOne
1,111111
2,897823
3,235473
4,222222
Contents of fileTwo
1,111111,A,1,2
4,222222,A,2,2
5,374632,A,3,2
6,374654,A,4,2
Final File should be:
1,111111,A,1,2... (9 Replies)
Hello everyone!!
I am not completely new to shell script but I havent been able to find the answer to my problem and I'm sure there are some smart brains here up for the challenge :D.
I have several CSV files that I need to combine into one, but I also need to know where each row came from.... (7 Replies)
Friends,
I need help with the following in UNIX.
Merge all csv files in one folder considering only 1 header row and ignoring header of all other files.
FYI - All files are in same format and contains same headers.
Thank you (4 Replies)
:confused:Hello -- i just joined the forums. I am a complete noob -- only about 1 week into learning how to program anything... and starting with linux.
I am working in Linux terminal.
I have a folder with a bunch of txt files. Each file has several lines of html code. I want to combine... (2 Replies)
Hi all,
I have two separate csv files(comma delimited) file 1 and file 2.
File 1 contains
PAN,NAME,Salary
AAAAA5467D,Raj,50000
AAFAC5467D,Ram,60000
BDCFA5677D,Kumar,90000
File 2 contains
PAN,NAME,Dept,Salary
ASDFG6756T,Karthik,ABC,450000
QWERT8765Y,JAX,CDR,780000... (5 Replies)
I am trying to merge all csv files from source path into one single csv file in target. but getting error message:
hadoop fs -cat /user/hive/warehouse/stage.db/PK_CLOUD_CHARGE/TCH-charge_*.csv > /user/hive/warehouse/stage.db/PK_CLOUD_CHARGE/final/TCH_pb_charge.csv
getting error message:... (0 Replies)
Hi all,
i need help.
I have two csv files with a huge amount of data.
I need the first column of the first file, to be compared with the data of the second, to have at the end a file with the data not present in the second file.
Example
File1: (only one column)
profile_id
57036226... (11 Replies)
I have three files with similar pattern i need to merge all the coloumns side by side from all three files according to the first coloumn example as shown below
I mentioned 5 coloumns only in example but i have around 15 coloumns in each file.
file1:
Name,Samples,Error,95RT,90RT... (4 Replies)
Discussion started by: Raghuram717
4 Replies
LEARN ABOUT V7
pipe
PIPE(2) System Calls Manual PIPE(2)NAME
pipe - create an interprocess channel
SYNOPSIS
pipe(fildes)
int fildes[2];
DESCRIPTION
The pipe system call creates an I/O mechanism called a pipe. The file descriptors returned can be used in read and write operations. When
the pipe is written using the descriptor fildes[1] up to 4096 bytes of data are buffered before the writing process is suspended. A read
using the descriptor fildes[0] will pick up the data. Writes with a count of 4096 bytes or less are atomic; no other process can inter-
sperse data.
It is assumed that after the pipe has been set up, two (or more) cooperating processes (created by subsequent fork calls) will pass data
through the pipe with read and write calls.
The Shell has a syntax to set up a linear array of processes connected by pipes.
Read calls on an empty pipe (no buffered data) with only one end (all write file descriptors closed) returns an end-of-file.
SEE ALSO sh(1), read(2), write(2), fork(2)DIAGNOSTICS
The function value zero is returned if the pipe was created; -1 if too many files are already open. A signal is generated if a write on a
pipe with only one end is attempted.
BUGS
Should more than 4096 bytes be necessary in any pipe among a loop of processes, deadlock will occur.
ASSEMBLER
(pipe = 42.)
sys pipe
(read file descriptor in r0)
(write file descriptor in r1)
PIPE(2)