how can i redirect standard input? i dont remember :/, though could you redirec not from a command? i mean, to redirect always stdin and stout (1 Reply)
I tried copy the output files from find command into a directory.
Example,
find / -name core 2>/dev/null | xargs cp????
I have known that we can use xargs to execute command lines from standard input but how to use it in this case.
Or I can do something besides xargs. (2 Replies)
Dear...
I have a scrpit that contains multiple read command.... when I run the script I have to enter 3 variables so that I can get the output..
but, I dont want to put those 3 inputs manually every time... I want to make a shell that reads the 3 inputs from a file.
the script name is... (4 Replies)
Hello,
Could somebody please give me an awk example on how to read from the standard input.
It means as the "read" function in Korn shell.
Thx in advance ... (3 Replies)
Hello,
I am new to scripting.
How do I read multiple lines from the command line?
I know read reads one line, but if I have to read multiple lines, how should I do?
Thanks,
Prasanna (4 Replies)
So, I am new to shell scripting and have a few problems.
I know how to read from standard input but I do not know how to really compare it to say, a character. I am trying to compare it to a character and anything exceeding just a character, the user will get an output message, but the program... (7 Replies)
I have a program that requires the user to enter input values while it is being run
for example in bash
...
...
..
echo "Enter your input"
read input
echo $input
...
...
...I need to schedule this program with crontab, hence a problem, cronjobs run in the background, any ideas on how to... (10 Replies)
I want to use a content of a file as standard input to a program and dump the output to a file. However, when I try the following code:
./program < input.in > output.out
The output.out is empty. So, how can I handle this problem?
Thanks in advance! (11 Replies)
Just started learning Unix and received my first assignment recently. We haven't learned many commands and honestly, I'm stumped. I'd like to receive assistance/guidance/hints.
1. The problem statement, all variables and given/known data:
How do I write a shell script that takes in a file or... (4 Replies)
Discussion started by: fozilla
4 Replies
LEARN ABOUT MOJAVE
daemon
DAEMON(3) BSD Library Functions Manual DAEMON(3)NAME
daemon -- run in the background
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <stdlib.h>
int
daemon(int nochdir, int noclose);
DESCRIPTION
The daemon() function is for programs wishing to detach themselves from the controlling terminal and run in the background as system daemons.
The fork(2) system call is used; see CAVEATS below about the environment after a fork() (without a corresponding call to one of the exec rou-
tines). On Mac OS X, the use of this API is discouraged in favor of using launchd(8).
Unless the argument nochdir is non-zero, daemon() changes the current working directory to the root (/).
Unless the argument noclose is non-zero, daemon() will redirect standard input, standard output, and standard error to /dev/null.
RETURN VALUES
The daemon() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate
the error.
ERRORS
The daemon() function may fail and set errno for any of the errors specified for the library functions fork(2) and setsid(2).
SEE ALSO fork(2), launchd(8), setsid(2), sigaction(2)HISTORY
The daemon() function first appeared in 4.4BSD.
CAVEATS
There are limits to what you can do in the child process. To be totally safe you should restrict yourself to only executing async-signal
safe operations (see sigaction(2)) until such time as one of the exec functions is called. All APIs, including global data symbols, in any
framework or library should be assumed to be unsafe after a fork() unless explicitly documented to be safe or async-signal safe. If you need
to use these frameworks in the child process, you must exec. In this situation it is reasonable to exec yourself.
Unless the noclose argument is non-zero, daemon() will close the first three file descriptors and redirect them to /dev/null. Normally,
these correspond to standard input, standard output, and standard error. However, if any of those file descriptors refer to something else,
they will still be closed, resulting in incorrect behavior of the calling program. This can happen if any of standard input, standard out-
put, or standard error have been closed before the program was run. Programs using daemon() should therefore either call daemon() before
opening any files or sockets, or verify that any file descriptors obtained have values greater than 2.
The daemon() function temporarily ignores SIGHUP while calling setsid(2) to prevent a parent session group leader's calls to fork(2) and then
_exit(2) from prematurely terminating the child process.
BSD June 9, 1993 BSD