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Top Forums Shell Programming and Scripting Redirect string from bash stderr to user stdin Post 302998209 by fredestet on Saturday 27th of May 2017 09:28:40 AM
Old 05-27-2017
Redirect string from bash stderr to user stdin

Hi there,

I need to execute a command in the bash. The program prints some standard (output and) error and then wants the user to choose one of several options and type the according input. I am trying to solve this issue in a bash script but also running into some circular dependency. How can I combine these two things to a single bash call with only one execution of command? For the user input, i would usually write something like
Code:
echo $input | command

But $input must be read from stderr of command in advance which I would usually read as
Code:
input=$(command 2>&1 > /dev/null | awk '/some.*regexp$/ {print $2}')

I particularly don't want to execute command twice (once for extracting/saving the content of $input and once for feeding command with that input). Is there a way to combine the two calls in one? (BTW: both single commands work as I need them since I want to read from the stderr and don't need stdout at all.)

Many thanks in advance!
 

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RBASH(1)						      General Commands Manual							  RBASH(1)

NAME
rbash - restricted bash, see bash(1) RESTRICTED SHELL
If bash is started with the name rbash, or the -r option is supplied at invocation, the shell becomes restricted. A restricted shell is used to set up an environment more controlled than the standard shell. It behaves identically to bash with the exception that the follow- ing are disallowed or not performed: o changing directories with cd o setting or unsetting the values of SHELL, PATH, ENV, or BASH_ENV o specifying command names containing / o specifying a file name containing a / as an argument to the . builtin command o specifying a filename containing a slash as an argument to the -p option to the hash builtin command o importing function definitions from the shell environment at startup o parsing the value of SHELLOPTS from the shell environment at startup o redirecting output using the >, >|, <>, >&, &>, and >> redirection operators o using the exec builtin command to replace the shell with another command o adding or deleting builtin commands with the -f and -d options to the enable builtin command o using the enable builtin command to enable disabled shell builtins o specifying the -p option to the command builtin command o turning off restricted mode with set +r or set +o restricted. These restrictions are enforced after any startup files are read. When a command that is found to be a shell script is executed, rbash turns off any restrictions in the shell spawned to execute the script. SEE ALSO
bash(1) GNU Bash-4.0 2004 Apr 20 RBASH(1)
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