BASH - read does not wait for user input in some circumstances
Hello.
I am running 2 scripts : script_1 and script_2
These scripts are run as root
Script 2 contains :
When calling from a console
I get :
and the program wait until I hit enter or CTRL-C
Now this script is call from script_1
When calling from a console
I get :
and the program wait until I hit enter or CTRL-C
So same behavior.
If script_1 is :
Then calling script_1
give
and the program wait until I hit enter or CTRL-C
So same behavior.
In real life, the list of users come from a file
Now script_1 is :
Then calling script_1
give
Now script 2 does not wait for "enter" or "CTRL-C"
I think that the problem come from because there is 2 read commands in sequence
One to get user name one by one
And the second which wait for user input.
Any idea to make this working ?
---------- Post updated at 17:02 ---------- Previous update was at 16:24 ----------
Finally found info on
HTML Code:
http://unix.stackexchange.com/questions/26601
Make change in script_1
before :
after correction :
Thread is closed.
The problem is quite a simple one. One of the many things inherited by a child process from the parent are the standard file descriptors (0 - standard input, 1-standard output, 2-standard error). Also, read reads from standard input.
When you are running script 1 without any redirection, standard input for both script 1 and 2 comes from the terminal and hence, the read command waits for a line.
When you are running script 1 with standard input source being changed to the file, standard input for script 2 also comes from the file and the read in script 2 will read the next line from the file (or fail if input has been exhausted). In any case, it will go on to the next set of statements.
If you need to read that line (looks like that's a dummy read; you just want to wait, right?) from the terminal, you may include a statement such as
at the beginning of script 2. But, this will also make the terminal the input source for other commands (only in script 2; script 1 will continue reading from the file as a child cannot affect its parent) reading from standard input. But, I suggest this because I do not see any such statements in script 2.
Last edited by elixir_sinari; 10-29-2012 at 07:07 AM..
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