I am trying to call a command in batch file using "call" method and whatever is the output of that command, I want to write in a file.
I went through from this link but cannot find the answer.
I am using this command
call %confPath% GetIniString %datFile% Keyname name >%newFile% >&1
but it creates a empty file always. How can i write the output of above command in the file?
Thanks in advance.
>%newFile% redirects the standard output to a file. in >&1, the 1 stands for standard output, and if no stream is specified, standard output is the default, so >&1 redirects on itself, although it was already redirected with the first command. So, this is illegal and shouldn't produce a file at all. In my tests, this just aborts with an errormessage.
The usual idiom 2>&1, OTOH, redirects stream 2, which is standard ERROR, to standard output, which ensures that both output and error messages end up in the file.
Related
I would like to know if it's possible to get the output redirection file name as a parameter in bash?
For example :
./myscript.sh parameter1 > outputfile
Is there a way to get "outputfile" as a parameter like $2? In my script I have to do few operations in outputfile but I don't know which file I have to update... The second problem is, this script is already running and used by several tasks so I cannot change the user input...
Best regards
Redirections are not parameters to the program. When a program's output is redirected, the shell opens the file and connects file descriptor 2 to it before running the program. The program then simply writes to fd 2 (aka stdout) and it goes to the file.
On Linux and similar systems you can use /dev/stdout, which is a symbolic link to the process's stdout file.
Which command in Windows command script (.cmd) accepts pipe (so, no error "The Process tried to write to a nonexistent pipe." generated), but generates no output itself, including output to StdErr? I need to not touch normal StdErr output (keep in mind, pipe transports only StdOut). I can't use null device, due to it's not installed in the system.
For example, command|rem generates mentioned error. But I want no error output, except generated by command, so rem is not suitable command for needed purpose.
Main aim is the script speed. So, don't offer extensive constructions, please.
should be break(or set/p= ?) as it is internal command prompt command (i.e. no external process started ) and generally do nothing.Though I suppose if you are searching for executable packed with the windows answer will be different.
The cd . command is what you are looking for. I used it to create empty files. This way, command | cd . works and echo Hello >&2 | cd . show "Hello" in the screen! This works as a filter that just blocks Stdout (interesting).
I need to start up a Golang web server and leave it running in the background from a bash script. If the script in question in syntactically correct (as it will be most of the time) this is simply a matter of issuing a
go run /path/to/index.go &
However, I have to allow for the possibility that index.go is somehow erroneous. I should explain that in Golang this for something as "trival" as importing a module that you then fail to use. In this case the go run /path/to/index.go bit will return an error message. In the terminal this would be something along the lines of
index.go:4:10: expected...
What I need to be able to do is to somehow change that command above so I can funnel any error messages into a file for examination at a later stage. I tried variants on go run /path/to/index.go >> errors.txt with the terminating & in different positions but to no avail.
I suspect that there is a bash way to do this by altering the priority of evaluation of the command via some judiciously used braces/brackets etc. However, that is way beyond my bash capabilities. I would be most obliged to anyone who might be able to help.
Update
A few minutes later... After a few more experiments I have found that this works
go run /path/to/index.go &> errors.txt &
Quite apart from the fact that I don't in fact understand why it works there remains the issue that it produces a 0 byte errors.txt file when the command goes to completion without Golang throwing up any error messages. Can someone shed light on what is going on and how it might be improved?
Taken from man bash.
Redirecting Standard Output and Standard Error
This construct allows both the standard output (file descriptor 1) and the standard error output (file descriptor 2) to be redirected to the file whose name is the expansion of word.
There are two formats for redirecting standard output and standard error:
&>word
and
>&word
Of the two forms, the first is preferred. This is semantically equivalent to
>word 2>&1
Appending Standard Output and Standard Error
This construct allows both the standard output (file descriptor 1) and the standard error output (file descriptor 2) to be appended to the file whose name is the expansion of word.
The format for appending standard output and standard error is:
&>>word
This is semantically equivalent to
>>word 2>&1
Narūnas K's answer covers why the &> redirection works.
The reason why the file is created anyway is because the shell creates the file before it even runs the command in question.
You can see this by trying no-such-command > file.out and seeing that even though the shell errors because no-such-command doesn't exist the file gets created (using &> on that test will get the shell's error in the file).
This is why you can't do things like sed 'pattern' file > file to edit a file in place.
What I would like to do is:
run a ruby script...
that executes a shell command
and redirects it to a named pipe accessible outside the script
from the system shell, read from that pipe
That is, have the Ruby script capture some command output and redirect it in such a way that it's connectable to from outside the script?
I want to mention that the script cannot simply start and exit, since it's a REPL. The idea is that using the REPL you would be able to run a command and redirect its output elsewhere to consume it.
Using abort and an exit message, will pass the message to STDERR (and the script will fail with exit code 1). You can pass this shell command output in this way.
This is possibly not the only (or best) way, but it has worked for me in the past.
[edit]
You can also redirect the output to a file (using standard methods), and read that file outside the ruby script.
require 'open3'
stdin, stderr, status = Open3.capture3(commandline)
stdin.chomp #Here, you should ge
Incase, if someone wanted to use you can get the output via stdin.chomp
I want to redirect complete make output to a file.
I tried redirecting the stdout and stderr with the following command:
make >aks_file.txt 2>&1 &
But that is not redirecting the EXACT complete output which is otherwise generated by issuing just make (some lines are missing)
Am I missing something?
Some programs (either make or what make invokes) can detect whether their output streams are attached to the console or file and change their behavior (what they output) accordingly. To be more specific, more details on what output exactly is missing and by what program it is being generated when ran without redirection is needed.