Is there a location where kernel build logs are found while doing standard kernel compilation.
One way is to redirect the output to the file.
source <build_script> > build_log_file.txt
It goes into stdout and stderr. If you want it to go to a file instead you can:
make > <logfile> 1>&2
If you want the output to go into file and the screen you can
make 2>&1 | tee <logfile>
Related
I want to write a program that can capture the input/output of a pseudo terminal without it affecting the original terminal. It can be likened to pointing script to a /dev/pts/<n>.
Use Case: A user ssh's into my machine and runs an interactive tool. With audit, I can see commands running but I need to see the output also. I can listen in on /dev/pts/<n> but then the original logged in user does not get the output.
I want to write my own program to handle this case. Is this problem actually solvable and if so, where should I be looking to find a solution?
That's solvable by using ptrace(2) on the ssh server process which handles to master end of the pseudo-terminal (which is usually the parent process of the shell running in the terminal).
You can start with strace which is itself using ptrace(2), e.g.
strace -p <pid> -e trace=read,write \
-e read=<fds opened to /dev/ptmx> \
-e write=<fds opened to /dev/ptmx>
This will show you everything that's read or written to that pseudo-terminal. You can get the "fds opened to /dev/ptmx" from ls -l /proc/<pid>/fd.
You can then look at what strace is doing -- e.g. by stracing strace itself with
strace -e trace=ptrace,process_vm_readv strace ...
and by studying its source code.
You can of course modify the ssh server itself to log all that info, or just tweak its config options (e.g. LogLevel -- which can be modified on a per-user or connecting host basis).
On the docker image debian:stretch-slim, couldn't delete a specific folder on a NFS drive, using rm -rf /folder-name as root (or rm-rf * after entering the folder-name).
Got the following error back:
rm: cannot remove 'test-ikmgfjhv/dev/.nfse47cf31c6b1dd52500000009': Device or resource busy
After a lot of searching, eventually got to the following link:
https://uisapp2.iu.edu/confluence-prd/pages/viewpage.action?pageId=123962105
Which Describes exactly why those files exist in NFS and how to handle them.
As I wasn't using the same machine the process runs on (another container), so in my case, I had to work around that and first make sure the process using the file is being killed on the first machine, then try to delete it on the second one, according to the project's needs.
It is possible that the .nfs file is attached to a process that is busy or running (like an open file, for example, a vim file).
For example, if the hidden file is .nfs000000000189806400000085, run this command to get the pid:
lsof .nfs000000000189806400000085
this will output the PID and other info related to that file
then kill the process:
kill - 9
Be aware that if the file was not saved you will lose the information.
While running any command if you get error like :
/home/mmandi/testcases/.nfs000000e75853 :device or resource busy.
Go to the directory where this file is being shown.
For e.g - In this case : /home/mmandi/testcases/
Do following :
# ls -la : This will display contents of the directory along with files starting with "."
Here it displays the .nfs000000e7585 file.
# lsof .nfs000000e7585
This will list down the PID
# Use Kill -9 PID.
I'm developing a C++ library that has a piece of shell script code that return the name of a specific serial port. When I run this script in console either X64 desktop or Arm enviorment the script returns the right answer. My problem ocur when I execute the same script inside of the library, the returns shows bad formed string like ÈÛT¶ÈÛT¶¨a , but the expected is /dev/ttyACM0.
The script that run inside of library:
Script
bash -c 'for sysdevpath in $(find /sys/bus/usb/devices/usb*/ -name dev);do(syspath="${sysdevpath%/dev}";devname="$(udevadm info -q name -p $syspath)";[[ "$devname" == "bus/"* ]]&& continue;teste="$(udevadm info -q property --export -p $syspath | grep -i "company_name")";if [[ ! -z "${teste// }" && $devname == *"ttyACM"* ]]; then echo "/dev/$devname";fi);done;' 2> /dev/null
The following piece of code is used to save the content returned by the script into a file.
code c++
pfFile = fopen(CONFIG_FILE, "w+");
fwrite(result,strlen(result), 1, pfFile);
fclose(pfFile);
return 0;
Besides you didn't include what is result and where it comes from in your C++ code; you selected the hardest way to do this. Code running shell scripts inside a library most likely cause nothing but headaches.
Basically you can create an udev rule for your device to create an unique and stable file in /dev to access it. You can create one like this one in the ArchWiki
KERNEL=="video[0-9]*", SUBSYSTEM=="video4linux", SUBSYSTEMS=="usb", ATTRS{idVendor}=="05a9", ATTRS{idProduct}=="4519", SYMLINK+="video-cam1"
I successfully compiled a MUD source code, and it says in the instructions to start up the server using
nohup ./startup &
although when I do this it gives me this error:
$ nohup: ignoring input and appending output to `nohup.out'
nohup: failed to run command `./startup': Permission denied
I have looked all over the internet to find the answer. A few of them said to put my cygwin directory in the root folder (I am using windows 7) and its directory is C:\cygwin
so thats not a problem.. Can anyone help me with this please??
Try chmod +x startup, maybe your startup file is not executable.
From "man nohup":
If the standard output is a terminal, all output written by the named
utility to its standard output shall be appended to the end of the
file nohup.out in the current directory. If nohup.out cannot be
created or opened for appending, the output shall be appended to the
end of the file nohup.out in the directory specified by the HOME
environment variable. If neither file can be created or opened for
appending, utility shall not be invoked. If a file is created, the
file's permission bits shall be set to S_IRUSR | S_IWUSR.
My guess is that since "sh -c" doesn't start a login shell, it is inheriting the environment of the invoking shell, including the HOME environment variable, and is trying to open it there. So I would check the permissions of both your current directory and $HOME. You can try to touch test.txt in current directory or $HOME to see if you can perform that command.
As staticx writes, check the permissions of the directory (and the user) - and the executable.
Instead of using nohup:
check if nohup is needed at all, try ./startup </dev/null >mud.out 2>mud.err &, then close the terminal window and check if it is running
or just run ./startup in a screen session and detach it (<ctrl>+<a>,<d>)
I have a Ruby script that I have developed that allows me to install and build multiple C++ packages. I am able to execute the Ruby script and install the packages with no errors.
However, I would like to be able to capture all of the output, including cerr, to a "log" file of my choosing. I am able to redirect Ruby's cerr and standard output, but I cannot capture the bash commands: qmake, make, or make install cerr. The output still flows to the terminal.
I want to be able to run the Ruby script and not see any debug messages from any qmake, make, or make install bash commands, but be able to check a log file later for build results.
you can do
require 'open3'
log = File.new("#{your_log_dir}/script.log", "w+")
command = "make"
Open3.popen3(command) do |stdin, stdout, stderr|
log.puts "[OUTPUT]:\n#{stdout.read}\n"
unless (err = stderr.read).empty? then
log.puts "[ERROR]:\n#{err}\n"
end
end
%x[#insert bash command here] captures the response. If you need to handle STDERR you'll want to pipe it to STDOUT I believe.
To directly dump stdout and stderr of a child process to files:
cmd = ['ls', '-ahl', '/my/directory'] # example directory listing
pid = Process.spawn *cmd, out: '/path/to/stdout/log', err: '/path/to/stderr/log'
Process.wait pid
You may also pass file descriptors instead of path strings.
If you're on Mac OS or Linux, you can use standard redirection and a simple shell call if you want to capture the STDOUT and STDERR to a variable in your script:
asdf = `ls foo 2>&1`
asdf # => "ls: foo: No such file or directory\n"
2>&1 simply redirects STDERR in the command output to STDOUT, which is captured when the program runs.
If you want to redirect both STDOUT and STDERR to the same file for later, use:
`ls foo > output.log 2>&1`
The STDOUT has to be redirected before &2>1 will take effect, but that will capture both.
For more information see the "Redirect" section of man sh.