Sponsored Content
Top Forums UNIX for Dummies Questions & Answers Redirection related clarifications required... Post 302227435 by marconi on Thursday 21st of August 2008 08:15:08 AM
Old 08-21-2008
Redirection related clarifications required...

There are two files named goody and good. Please look at their single line contents:-
$ cat goody
hi m goody
$ cat good
hi m good

1)
$ cat goody < good
hi m goody

When we give cat, a file to read from, standard input is ignored.
As such, the above operation will just display contents of goody.


2)
$ cat > goody < good
$ cat goody
hi m good
$ cat good
hi m good

What will be the output of the above command ? I think the command takes input from file good and then overwrites in goody and prints on terminal screen.

3) Whats the difference between a) cat goody >>= good and b) cat goody >> good

4) Whats the difference between a) cat goody >= good and b) cat goody > good

5) Whats the difference between cat < good and cat << good


Thanks a lot in advance.

Best Regards,
Marconi.
 

10 More Discussions You Might Find Interesting

1. Programming

Help with redirection

Here is my problem. I don't know make this redirection thing work. The output file (called output.c) looks like this #include<stdio.h> int main() { int k; int m; print f("%d\n", k); printf("%d\n", m); return 0; } the input file(called input.c) is this #include<stdio.h> int... (2 Replies)
Discussion started by: Shallon1
2 Replies

2. Shell Programming and Scripting

redirection

Hi, The code below works, it's a part of a bash shell script that serve to search a pattern $pattern_da_cercare in the files contained in a directory $directory_iniziale. Now the proble is: How can I redirect stderr to a file? PS: so I want to redirect ALL the errors to a file. I tryed... (9 Replies)
Discussion started by: DNAx86
9 Replies

3. UNIX for Advanced & Expert Users

password required when using input redirection

Hello, I need to change user and run some commands by using a script. lets say, I'm using su - someuser << start password required -----> how can I enter the password here command 1 command 2 command 3 command 4 start While trying to run this I got the following message: "standard... (2 Replies)
Discussion started by: Alalush
2 Replies

4. Shell Programming and Scripting

Scripting related .

Could any body give the solution/script to get the below... 1.script will run and detcect the files having 0kb size , and give the solution in a out put file.(Will search the file in the path let say /abc/M/) 2.Same as the above also send a mail to your mails id , with the file name stating... (13 Replies)
Discussion started by: alexMar
13 Replies

5. Shell Programming and Scripting

Getting required fields from a test file in required fromat in unix

My data is something like shown below. date1 date2 aaa bbbb ccccc date3 date4 dddd eeeeeee ffffffffff ggggg hh I want the output like this date1date2 aaa eeeeee I serached in the forum but didn't find the exact matching solution. Please help. (7 Replies)
Discussion started by: rdhanek
7 Replies

6. UNIX for Dummies Questions & Answers

Help with Redirection

Hi Guys, I m new to UNIX and new to this forum. Was wondering if someone can help me understand redirection (standard input output pipeline etc) for starters, not too sure what this would mean who | sort > sortedfile | pr | lp im starting to understand common commands but when throwing... (2 Replies)
Discussion started by: jmack123
2 Replies

7. Shell Programming and Scripting

I/O redirection

Hello everyone,I'm reading a book and there's code fragment: exec 3>&1 ls -l 2>&1 >&3 3>&- | grep bad 3>&- exec 3>&- It says that the red part of that code does not close fd 3 but the green does close the fd 3.I can't understand that.....Why?Any predicate will be appreciated.:) (18 Replies)
Discussion started by: homeboy
18 Replies

8. Shell Programming and Scripting

Redirection

Hello All, I am using the below script to gather various tools running by the user, we have more than 100 tools running on the server so my challenge is to redirect memory & cpu load to the file with the name of the tool.so am using the below script i am stucking how to redirect to the file... (2 Replies)
Discussion started by: ajaincv
2 Replies

9. UNIX for Dummies Questions & Answers

about different redirection

explain the redirections 1>, 2>, 3>, ..... and 1< ,2<,3<..... where we use these things thanks Thread moved from AIX forum (2 Replies)
Discussion started by: tsurendra
2 Replies

10. Shell Programming and Scripting

need downloading related help...but its not related to unix

Hi All, I am trying to dowmload the zip file "zkManageCustomers.zip " but i dont have access. Can anyone help me to download this file See the below link- http://www.ibm.com/developerworks/opensource/library/wa-aj-open/index.html?ca=drs- Please help me as early as... (1 Reply)
Discussion started by: aish11
1 Replies
CAT(1)							    BSD General Commands Manual 						    CAT(1)

NAME
cat -- concatenate and print files SYNOPSIS
cat [-benstuv] [file ...] DESCRIPTION
The cat utility reads files sequentially, writing them to the standard output. The file operands are processed in command-line order. If file is a single dash ('-') or absent, cat reads from the standard input. If file is a UNIX domain socket, cat connects to it and then reads it until EOF. This complements the UNIX domain binding capability available in inetd(8). The options are as follows: -b Number the non-blank output lines, starting at 1. -e Display non-printing characters (see the -v option), and display a dollar sign ('$') at the end of each line. -n Number the output lines, starting at 1. -s Squeeze multiple adjacent empty lines, causing the output to be single spaced. -t Display non-printing characters (see the -v option), and display tab characters as '^I'. -u Disable output buffering. -v Display 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), more(1), pr(1), sh(1), tail(1), vis(1), zcat(1), setbuf(3) Rob Pike, "UNIX Style, or cat -v Considered Harmful", USENIX Summer Conference Proceedings, 1983. STANDARDS
The cat utility is compliant with the IEEE Std 1003.2-1992 (``POSIX.2'') specification. The flags [-benstv] 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! The cat utility does not recognize multibyte characters when the -t or -v option is in effect. BSD
March 21, 2004 BSD
All times are GMT -4. The time now is 06:30 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy