I want to get the output of tail -f /var/log/apache2/error.log | grep “trace1” into a file. But tail -f /var/log/apache2/error.log | grep “trace1” > output.txt does not work, while the first command gives an output in my terminal window as expected. I guess it has to do with the follow-parameter, because if I omit the “-f”, the output file is
Tag: redirect
Is pipe in linux asynchronous or not?
I thought that when i running below commands Linux process will be when sleep 10 is end -> sleep 2 (when sleep 2 is end)-> sleep 5 that’s i thought But in Linux bash sleep 10, sleep 2, sleep 5 are in ps same time Standard output of sleep 10 process will be redirected to sleep 5’s process But, in
Shell script: Redirect output of program to changing files
My goal: I would like to redirect the stdout output of my program foo to a changing output file depending on the running time of the program. The program foo itself is listening on a bsd socket for arriving packets and displays information contained in them. So essentially, after running the program foo for 10 minutes, I would like to
Does an argument after a redirection do anything?
Is any argument after a redirection ignored, or does it have any unintended consequences? I was surprised to find that a typo I made in my bash script made absolutely no difference because it was specified after a redirect. E.g. I expected it to complain about something like this But it doesn’t throw any errors. I have to add a
no such file or directory after redirection – simple command line program
Im programming a shell. This is a small piece of it that handles redirects. I only included the snippet that is causing the error. This portion of the program is supposed to take a command/argument line and execute the line accordingly. The wc < junk > junk2 is an example of a command line input and for some reason when
Spawn process and redirect current bash script’s output to it
How can I spawn a new background process from a bash script and redirect the current script’s stdout/stderr to that process’s stdin using fd redirection? I know of a few ways to accomplish the same effect, such as using a named pipe or a temporary file, using coprocs, or running the whole script in a subshell and redirecting the ouptut
Redirecting output of a program to a rotating file
I am trying to redirect the output of a continuously running program to a file say error_log. The command I am using looks like this, where myprogram.sh runs continuously generating data and writing to /var/log/httpd/error_log myprogram.sh >> /var/log/httpd/error_log Now I am using logrotate to rotate this file per hour. I am using create command in logrotate so that it renames
How to force HTTP to HTTPS with an exception?
So I had to force all connections via HTTP to go to HTTPS on a specific folder (e.g. “public_html/folder1”). I found a tutorial somewhere and used the following in an .htaccess file: Problem is, I have a folder inside that folder1 which should be allowed to be accessed via HTTP and not just HTTPS, how do I make an exception?
system call open() creating executable
So my code creates and writes to the out_file properly. However, the file is an executable for some reason. I think the fault is in my open() call but I can’t seem to find why. Answer man 2 open explains why: So if you want a file that’s not executable, you can use: 0666 will suggest read/write for all (equivalent
sed – Piping a string before the last line in a file
I have a command that prints a single line. I want to add/pipe this line to a file, just above its last line. I just find an empty line in the correct place, above the last line. I notice that when I add any string as ‘$i foo’, the “foo” gets printed in the correct place, but I want the