Stdio (standard out) is 1 (in this context) stderr is 2. I suspect you want to redirect stderr, meaning 2/dev/null As to where, I'm not exactly sure what you're doing in that line so I would rather not hazard a guess. – Petro Jun 29 '16 at 19:00. 在Stevens的UNIX网络编程中,他提到重定向stdin,stdout和stderr,这在设置守护进程时是必需的.他使用以下C代码 /. redirect stdin, stdout, and stderr to /dev/null./ open.
Q. How do I redirect stderr to stdout? How do I redirect stderr to a file?
A. Bash and other modern shell provides I/O redirection facility. There are 3 default standard files (standard streams) open:
[a] stdin – Use to get input (keyboard) i.e. data going into a program.
A. Bash and other modern shell provides I/O redirection facility. There are 3 default standard files (standard streams) open:
[a] stdin – Use to get input (keyboard) i.e. data going into a program.
If you indeed used command /bin/null on CentOS, you have created a common file file named /bin/null on your system. You may say 'It worked!' , if you want.This file now contains the stdout and stderr output of your command.Usually, in /bin/ there are only executable files. And usually, only the root user is allowed to create files there. So if that file is there, you did run your command as.
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[b] stdout – Use to write information (screen)
[c] stderr – Use to write error message (screen)
Understanding I/O streams numbers
The Unix / Linux standard I/O streams with numbers:
Handle | Name | Description |
0 | stdin | Standard input |
1 | stdout | Standard output |
2 | stderr | Standard error |
Redirecting the standard error stream to a file
The following will redirect program error message to a file called error.log:
$ program-name 2> error.log
$ command1 2> error.log
Redirecting the standard error (stderr) and stdout to file
Linux Redirect Error To Null
Use the following syntax:
OR
Another useful example:
$ command-name &>file
OR
$ command > file-name 2>&1
Another useful example:
# find /usr/home -name .profile 2>&1 | more
Redirect stderr to stdout
Use the command as follows:
$ command-name 2>&1
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I‘m a new Linux system user. How can I redirect command error output /dev/null on a Linux or Unix-like system using Bash shell?Cron Redirect Stderr And Stdout To Dev Null
Your shell comes with three file descriptors as follows:
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- stdin – 0 – Standard Input (usually keyboard or file)
- stdout – 1 – Standard Output (usually screen)
- stderr – 2 – Standard Error (usually screen)
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What is a null (/dev/null) file in a Linux or Unix-like systems?
/dev/null is nothing but a special file that discards all data written to it. The length of the null device is always zero. In this example, first, send output of date command to the screen and later to the /dev/null i.e. discards date command output:
Syntax: Standard Error (stderr -2 no) to a file or /dev/null
The syntax is as follows:
In this example, send output of find command to /dev/null:
The following example will cause the stderr ouput of a program to be written to a file called errors.txt:
$ find /etc -type f -name '*' 2>/dev/null
The following example will cause the stderr ouput of a program to be written to a file called errors.txt:
$ find /etc/ -type f -name '*' 2> errors.txt
Linux and Unix redirect all output and error to file
The syntax is:
If you want both stderr and stdout in same file, try:
Use cat command to display log.txt on screen:
cat log.txt
See man pages for more information – ksh(1).
Csh Stderr To Dev/null
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