2>&1 is an operator which duplicates file descriptors, in this case stderr (2) is duplicated onto stdout (1) (See the Duplicating File Descriptors in the bash manual)
In
the combined stderr and stdout from command1 will be piped as stdin to command2
see this
cat < Files
return the cointent of Files
but
cat files
return the same result
WHI???
this command
lp -f """PRINTER" < cat files
not print the content of files (1 Reply)
Dear friends,
please tell me how to find the files which are existing in the current directory, but it sholud not search in the sub directories..
it is like this,
current directory contains
file1, file2, file3, dir1, dir2
and dir1 conatins
file4, file5
and dir2 contains
file6,... (9 Replies)
I intend to find the path/full location of a file(filename given by user thru "read filenme") using "find" or any other command and then store it's output in a variable for some other processing.
But struggling to put all things together (i.e finding the fully qualified location of that file and... (4 Replies)
Hi,
I have line in input file as below:
3G_CENTRAL;INDONESIA_(M)_TELKOMSEL;SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL
My expected output for line in the file must be :
"1-Radon1-cMOC_deg"|"LDIndex"|"3G_CENTRAL|INDONESIA_(M)_TELKOMSEL"|LAST|"SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL"
Can someone... (7 Replies)
I want to list all files/lines which except those which contain the pattern ' /proc/' OR ' /sys/' (mind the leading blank).
In a first approach I coded:
find / -exec ls -ld {} | grep -v ' /proc/| /sys/' \; > /tmp/list.txt
But this doesn't work. I got an error (under Ubuntu):
grep:... (5 Replies)
Hi All,
I am new here but I have a scripting question that I can't seem to figure out with the "find" cmd.
What I am trying to do is to only have to run a single find cmd parsing the directories and output the different file types to induvidual files and I have been running into problems.... (3 Replies)
Which one of the following are more accurate and why?
nohup myScript.sh 1>nohup_$(date +%Y%m%d%H%M%S).out 2>&1 &
nohup myScript.sh 1>>nohup_$(date +%Y%m%d%H%M%S).out 2>&1 &
nohup myScript.sh >nohup_$(date +%Y%m%d%H%M%S).out 2>&1 &
nohup myScript.sh >>nohup_$(date +%Y%m%d%H%M%S).out 2>&1 &... (3 Replies)
How to use "mailx" command to do e-mail reading the input file containing email address, where column 1 has name and column 2 containing “To” e-mail address
and column 3 contains “cc” e-mail address to include with same email.
Sample input file, email.txt
Below is an sample code where... (2 Replies)
Hi,
I have to redirect output of the command "perldoc perllocal" to new file which
contains all the perl module installed.
Currently using
perldoc perllocal >> mod_data
This does not contain all perl modules installed locally on machine, and each character is doubled.
Please... (3 Replies)
Discussion started by: asak
3 Replies
LEARN ABOUT REDHAT
stdin
STDIN(3) BSD Library Functions Manual STDIN(3)NAME
stdin, stdout, stderr -- standard I/O streams
SYNOPSIS
#include <stdio.h>
extern FILE *stdin;
extern FILE *stdout;
extern FILE *stderr;
DESCRIPTION
Under normal circumstances every Unix program has three streams opened for it when it starts up, one for input, one for output, and one for
printing diagnostic or error messages. These are typically attached to the user's terminal (see tty(4)) but might instead refer to files or
other devices, depending on what the parent process chose to set up. (See also the ``Redirection'' section of sh(1) .)
The input stream is referred to as ``standard input''; the output stream is referred to as ``standard output''; and the error stream is
referred to as ``standard error''. These terms are abbreviated to form the symbols used to refer to these files, namely stdin, stdout, and
stderr.
Each of these symbols is a stdio(3) macro of type pointer to FILE, and can be used with functions like fprintf(3) or fread(3).
Since FILEs are a buffering wrapper around Unix file descriptors, the same underlying files may also be accessed using the raw Unix file
interface, that is, the functions like read(2) and lseek(2). The integer file descriptors associated with the streams stdin, stdout, and
stderr are 0, 1, and 2, respectively. The preprocessor symbols STDIN_FILENO, STDOUT_FILENO, and STDERR_FILENO are defined with these values
in <unistd.h>.
Note that mixing use of FILEs and raw file descriptors can produce unexpected results and should generally be avoided. (For the masochistic
among you: POSIX.1, section 8.2.3, describes in detail how this interaction is supposed to work.) A general rule is that file descriptors
are handled in the kernel, while stdio is just a library. This means for example, that after an exec, the child inherits all open file
descriptors, but all old streams have become inaccessible.
Since the symbols stdin, stdout, and stderr are specified to be macros, assigning to them is non-portable. The standard streams can be made
to refer to different files with help of the library function freopen(3), specially introduced to make it possible to reassign stdin, stdout,
and stderr. The standard streams are closed by a call to exit(3) and by normal program termination.
SEE ALSO sh(1), csh(1), open(2), fopen(3), stdio(3)CONSIDERATIONS
The stream stderr is unbuffered. The stream stdout is line-buffered when it points to a terminal. Partial lines will not appear until
fflush(3) or exit(3) is called, or a newline is printed. This can produce unexpected results, especially with debugging output. The buffer-
ing mode of the standard streams (or any other stream) can be changed using the setbuf(3) or setvbuf(3) call. Note that in case stdin is
associated with a terminal, there may also be input buffering in the terminal driver, entirely unrelated to stdio buffering. (Indeed, nor-
mally terminal input is line buffered in the kernel.) This kernel input handling can be modified using calls like tcsetattr(3); see also
stty(1), and termios(3).
CONFORMING TO
The stdin, stdout, and stderr macros conform to ANSI X3.159-1989 (``ANSI C89''), and this standard also stipulates that these three streams
shall be open at program startup.
Linux 2.0 March 24, 1998 Linux 2.0