In lots of Linux programs, like curl, wget, and anything with a progress meter, they have the bottom line constantly update, every certain amount of time. How do I do that in a bash script? All I can do now is just echo a new line, and that's not what I want because it builds up. I did come across something that mentioned "tput cup 0 0", but I tried it and it's kind of quirky. What's the best way?
6 Answers
{
for pc in $(seq 1 100); do
echo -ne "$pc%\033[0K\r"
usleep 100000
done
echo
}
The "\033[0K" will delete to the end of the line - in case your progress line gets shorter at some point, although this may not be necessary for your purposes.
The "\r" will move the cursor to the beginning of the current line
The -n on echo will prevent the cursor advancing to the next line
1 Comment
naumcho
awesome! great little example
You can also use tput cuu1;tput el (or printf '\e[A\e[K') to move the cursor up one line and erase the line:
for i in {1..100};do echo $i;sleep 1;tput cuu1;tput el;done
1 Comment
João Ciocca
That
printf '\e[A\e[K' was the only solution that actually did the trick for me! Thanks for sharing it!Small variation on linuts' code sample to move the cursor not to the beginning, but the end of the current line.
{
for pc in {1..100}; do
#echo -ne "$pc%\033[0K\r"
echo -ne "\r\033[0K${pc}%"
sleep 1
done
echo
}
Comments
printf '\r', usually. There's no reason for cursor addressing in this case.
Comments
To actually erase previous lines, not just the current line, you can use the following bash functions:
# Clears the entire current line regardless of terminal size.
# See the magic by running:
# { sleep 1; clear_this_line ; }&
clear_this_line(){
printf '\r'
cols="$(tput cols)"
for i in $(seq "$cols"); do
printf ' '
done
printf '\r'
}
# Erases the amount of lines specified.
# Usage: erase_lines [AMOUNT]
# See the magic by running:
# { sleep 1; erase_lines 2; }&
erase_lines(){
# Default line count to 1.
test -z "$1" && lines="1" || lines="$1"
# This is what we use to move the cursor to previous lines.
UP='\033[1A'
# Exit if erase count is zero.
[ "$lines" = 0 ] && return
# Erase.
if [ "$lines" = 1 ]; then
clear_this_line
else
lines=$((lines-1))
clear_this_line
for i in $(seq "$lines"); do
printf "$UP"
clear_this_line
done
fi
}
Now, simply call erase_lines 5 for example to clear the last 5 lines in the terminal.
1 Comment
Thomas Dickey
This is close(r), but ignores the possibility that there are fewer lines on the display than requested.
man terminfo(5) and look at the "cap-nam" column.
clr_eol=$(tput el)
while true
do
printf "${clr_eol}your message here\r"
sleep 60
done
'\r'rewinds to the beginning of the line. so just echo without a newline [-n] and then `echo -ne '\r' will go back to the beginning of the line.