My bash script gets into infinite loop

Question

I want to read repository names from file, show YES-NO-CANCEL dialog and then add the repository if user answers YES. So far, I have written this code:

g_dlg_yes=1
g_dlg_no=0
g_dlg_cancel=127

show_confirm_dlg()
{
    local prompt="$* [y(es)/n(o)/c(ancel)]: "
    local resp=""
    while [ "$resp" != "y" ] && [ "$resp" != "n" ] && [ "$resp" != "c" ]; do
        echo "$prompt"
        read resp
    done
    if [ "$resp" = "y" ]; then
        g_dlg_res=$g_dlg_yes
    elif [ "$resp" = "n" ]; then
        g_dlg_res=$g_dlg_no
    elif [ "$resp" = "c" ]; then
        g_dlg_res=$g_dlg_cancel
    else
        g_dlg_res=$g_dlg_cancel
    fi
}

add_repo()
{
    local filename="/home/stojan/repo.list"
    while read -r line
    do
        local repo_name=$line
        echo "Name read from file - $line"
        show_confirm_dlg "Add repository $repo_name?"
        local rc=$g_dlg_res
        if [ $rc -eq $g_dlg_yes ]; then
            add-apt-repository -y $repo_name
            ##echo $repo_name
        elif [ $rc -eq $g_dlg_no ]; then
            echo "Repository $repo_name rejected"
        elif [ $rc -eq $g_dlg_cancel ]; then
            echo "Script cancelled"
            exit 1
        else
            echo "Unknown response. Now cancelling..."
            exit 1
        fi
        echo "Press ENTER..."
        read _

    done < "$filename"
}

add_repo

The problem is that when I run this script I get stuck at show_confirm_dlg() and get into infinite loop. That is the script doesn't wait for my input and repeats confirmation over and over again.

How do you run the script? Any redirection/pipe there? Also, the code as shown just declares functions, it doesn't run anything. — choroba, Jan 25 '16 at 14:49

choroba · Accepted Answer · 2016-01-25T15:47:41.260

4

Using read reads from the standard input. When you use read inside a redirection, it doesn't read from the keyboard, it reads from whatever standard input is at that time.

C.f.:

{
    read a
    echo $a
} < <(echo Hello)

You can duplicate standard input somewhere else to be able to process several streams at the same time:

exec 3<&0          # fd3 now points to the initial stdin
{
    read a         # This reads the "Hello".
    read b <&3     # This reads from the keyboard.
    echo "$a, $b"

} < <(echo Hello)
exec 3<&-          # Close the fd3.

edited Jan 25 '16 at 15:47

answered Jan 25 '16 at 14:52

choroba

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In other words, there is only **one** "standard input". If you want to read from a file while controlling how that goes via user interaction at the terminal, you'll have to use two different input streams (not bring the file in via standard input (`<`)). – Jeff Y Jan 25 '16 at 15:00
Great! I got the idea! – Stojan Radjanovic Jan 25 '16 at 15:09
Any reason to not just use u1 and not the exec ? – 123 Jan 25 '16 at 15:12
@123: Updated. Reading from standard output seems weird. – choroba Jan 25 '16 at 15:47

score 0 · Answer 2 · edited May 23 '17 at 11:59

0

To get user input from the while...do loop, you can also do:

while [ "$resp" != "y" ] && [ "$resp" != "n" ] && [ "$resp" != "c" ]; do
    echo "$prompt"
    read resp </dev/tty
done

Please refer to this thread: Read input in bash inside a while loop

edited May 23 '17 at 11:59

Community

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1

answered Jan 26 '16 at 21:10

Quinn

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My bash script gets into infinite loop

2 Answers2