What exactly are you trying to do? Looks like you want to use pipes to communicate between the parent and child process. Standard output (stdout) of the parent process (ls) goes to the pipe which becomes the standard input (stdin) of the child process (sort). stdout of the child process...sort in this case...goes to a file.
Code:
ls | sort > file.out
Or are you sending the stdout of the parent process to a file which then becomes the stdin of the child process. Or if it's neither of the above. Be specific as to the one that best fits your needs.
Code:
ls > file.out
sort < file.out
Last edited by Yogesh Sawant; 02-26-2010 at 01:14 PM..
Reason: added code tags
Hi All.
I have the following simple shell program.
It reads a number from the "/user/amit/bldno";
for example: file "bldno" contains value "100"
After execution of the program the content should change to 101.
---------
#!/usr/bin/tcsh
V= `cat /user/amit/bldno`
echo $V
`rm -rf ... (1 Reply)
if test -z "$1"
then echo "you must give a filename or filepath"
else path=`dirname $1`
f_name =`basename $1`
if path="."
then path=`pwd`
fi
fi
cat $f_name $path >> index.txt
The only problem I am encountering with this is writing $path to index.txt
Keeps going gaga:
cat:... (1 Reply)
Hi All
I am new to C and trying to write a code to get a file as an output.
My text file should look like:
<var1>tab<var2>tab<var3>...upto the elements in an array
<varb1>tab<varb2>tab<varb3>...upto the elements in an array
Can someone please guide me how to write the code or a sample... (3 Replies)
Need to develop a unix shell script for the below requirement and I need your assistance:
1) search for file.log and file.bad file in a directory and read them
2) pull out "Load_Start_Time", "Data_File_Name", "Error_Type" from log file
4) concatinate each row from bad file as... (3 Replies)
Help needed...
Can you tell me how to compare the last two couple entries in a file and print their result in new file..:confused:
I have one file
Check1.txt
\abc1 12345
\abc2 12327
\abc1 12345
\abc2 12330
I want to compare the entries in Check1 and write to... (1 Reply)
I am looking to do a ls on a folder and have the output of the ls be structured so that is is modificaiton date, file name with the date in a format that is compatible with mysql. I am trying to build a table that stores the last modification date of certain files so I can display it on some web... (4 Replies)
Hi
I am trying to extract information out of a file but keep getting grep cant open errors
the code is below:
#bash
#extract orders with blank address details
#
# obtain the current date
# set today to the current date ccyymmdd format
today=`date +%c%m%d | cut -c24-31`
echo... (8 Replies)
Hi All,
We have a Unix program in oracle when we run the program this connects to specified ftp and will get the file into local server.
We are facing a problem like when file writing operations is not completed, this program is getting the incomplete file.
Could anyone please help me... (2 Replies)
Hi,
I have 1000 files names data1.txt through data1000.txt inside a folder. I want to write a script that will take each first line from the files and write them as output into a new file. How do I go about doing that? Thanks! (2 Replies)
Hello ,
I have comma delimited file with over 20 fileds that i need to do some validations on. I have to check if certain fields are null and then write the line containing the null field into a new file and then delete the line from the current file.
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Discussion started by: goddevil
2 Replies
LEARN ABOUT MOJAVE
pipe
PIPE(2) BSD System Calls Manual PIPE(2)NAME
pipe -- create descriptor pair for interprocess communication
SYNOPSIS
#include <unistd.h>
int
pipe(int fildes[2]);
DESCRIPTION
The pipe() function creates a pipe (an object that allows unidirectional data flow) and allocates a pair of file descriptors. The first
descriptor connects to the read end of the pipe; the second connects to the write end.
Data written to fildes[1] appears on (i.e., can be read from) fildes[0]. This allows the output of one program to be sent to another pro-
gram: the source's standard output is set up to be the write end of the pipe; the sink's standard input is set up to be the read end of the
pipe. The pipe itself persists until all of its associated descriptors are closed.
A pipe whose read or write end has been closed is considered widowed. Writing on such a pipe causes the writing process to receive a SIGPIPE
signal. Widowing a pipe is the only way to deliver end-of-file to a reader: after the reader consumes any buffered data, reading a widowed
pipe returns a zero count.
The generation of the SIGPIPE signal can be suppressed using the F_SETNOSIGPIPE fcntl command.
RETURN VALUES
On successful creation of the pipe, zero is returned. Otherwise, a value of -1 is returned and the variable errno set to indicate the error.
ERRORS
The pipe() call will fail if:
[EFAULT] The fildes buffer is in an invalid area of the process's address space.
[EMFILE] Too many descriptors are active.
[ENFILE] The system file table is full.
SEE ALSO sh(1), fork(2), read(2), socketpair(2), fcntl(2), write(2)HISTORY
A pipe() function call appeared in Version 6 AT&T UNIX.
4th Berkeley Distribution February 17, 2011 4th Berkeley Distribution
04-01-2008
