I'm using the bourne shell in UNIX, and am running into the following problem:
#!/bin/sh
while read line
do
echo $line
if [ $x = "true" ]
then
echo "something"
read choice
echo $choice
else
echo "something"
fi
done <file.txt
The problem I have here is that UNIX will not wait for user input in the read command - it just plows on through instead of waiting for what the user types in. How can I make unix wait for user input?
It is because you are asking the program to read from the file file.txt:
done <file.txt
Also looks like you have a typo here:
if [ $x = "true" ]
^^
which should be "$line".
Also note the ", without them your program will break if the word read from the file has a space in it.
The redirection of standard input by the <file.txt at the end of while ... done <file.txt affects the whole while loop, including the read choice as well as the read line. It's not just failing to stop - it's consuming a line of your input file too.
Here's one way to solve the problem...
You can save the original standard input by using the somewhat obscure (even by shell standards):
exec 3<&0
which opens file descriptor 3 to refer to the original file descriptor 0, which is the original standard input. (File descriptors 0, 1 and 2 are standard input, output and error respectively.) And then you can redirect just the input of read choice to come from file descriptor 3 by doing read choice <&3.
Complete working script (I wasn't sure where x was supposed to come from, so I just bodged it to make it work):
#!/bin/sh
x=true # to make the example work
exec 3<&0
while read line
do
echo $line
if [ $x = "true" ]
then
echo "something"
read choice <&3
else
echo "something"
fi
done <file.txt
I don't do much shell scripting, but i think 'read choice' should be 'read $choice'
