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⇤ ← Revision 1 as of 2007-05-02 23:23:02
Size: 725
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Size: 1136
Comment: echo -ne -> printf; explain the code a little. add an example loop for the function that is to be called within a loop.
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| echo -en "\b${sp:i++%${#sp}:1}" | printf "\b${sp:i++%${#sp}:1}" |
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| You can also use \r instead of \b. You can use pretty much any character sequence you want as well. If you want it to slow down, put a {{{sleep}}} command inside the loop. | The theory here is that each time the loop iterates, it displays the next character in the `sp` string, wrapping around as it reaches the end (where `i` is the position of the current character to display and `${#sp}` is the length of the `sp` string). |
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| To use as a function called from a loop on every iteration, for example: | The `\b` string is replaced by a 'backspace' character. Alternatively, you could play with `\r` to go back to the beginning of the line. If you want it to slow down, put a {{{sleep}}} command inside the loop (after the printf). If you already have a loop which does a lot of work, you can call the following function at the beginning of each iteration in that loop to update the spinner every time an iteration of your loop begins: |
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| echo -ne "\b${sp:sc++:1}" | printf "\b${sp:sc++:1}" |
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| endspin() { printf "\r%s\n" "$@" } until work_done; do spin some_work done endspin |
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| When printing the next output line (ie when the spin is over) use: {{{ echo -e "\r$line" }}} or: {{{ echo -en '\r'; echo "$line" }}} |
Can I do a spinner in Bash?
Sure.
i=1
sp="/-\|"
echo -n ' '
while true
do
printf "\b${sp:i++%${#sp}:1}"
doneThe theory here is that each time the loop iterates, it displays the next character in the sp string, wrapping around as it reaches the end (where i is the position of the current character to display and ${#sp} is the length of the sp string).
The \b string is replaced by a 'backspace' character. Alternatively, you could play with \r to go back to the beginning of the line.
If you want it to slow down, put a sleep command inside the loop (after the printf).
If you already have a loop which does a lot of work, you can call the following function at the beginning of each iteration in that loop to update the spinner every time an iteration of your loop begins:
sp="/-\|"
sc=0
spin() {
printf "\b${sp:sc++:1}"
((sc==4)) && sc=0
}
endspin() {
printf "\r%s\n" "$@"
}
until work_done; do
spin
some_work
done
endspinA similar technique can be used to build progress bars.