How to add a progress bar to a shell script?

Question

When scripting in bash or any other shell in *NIX, while running a command that will take more than a few seconds, a progress bar is needed.

For example, copying a b

Answer 1

I did a pure shell version for an embedded system taking advantage of:

• /usr/bin/dd's SIGUSR1 signal handling feature.

  Basically, if you send a 'kill SIGUSR1 $(pid_of_running_dd_process)', it'll output a summary of throughput speed and amount transferred.

• backgrounding dd and then querying it regularly for updates, and generating hash ticks like old-school ftp clients used to.

• Using /dev/stdout as the destination for non-stdout friendly programs like scp

The end result allows you to take any file transfer operation and get progress update that looks like old-school FTP 'hash' output where you'd just get a hash mark for every X bytes.

This is hardly production quality code, but you get the idea. I think it's cute.

For what it's worth, the actual byte-count might not be reflected correctly in the number of hashes - you may have one more or less depending on rounding issues. Don't use this as part of a test script, it's just eye-candy. And, yes, I'm aware this is terribly inefficient - it's a shell script and I make no apologies for it.

Examples with wget, scp and tftp provided at the end. It should work with anything that has emits data. Make sure to use /dev/stdout for programs that aren't stdout friendly.

#!/bin/sh
#
# Copyright (C) Nathan Ramella (nar+progress-script@remix.net) 2010 
# LGPLv2 license
# If you use this, send me an email to say thanks and let me know what your product
# is so I can tell all my friends I'm a big man on the internet!

progress_filter() {

        local START=$(date +"%s")
        local SIZE=1
        local DURATION=1
        local BLKSZ=51200
        local TMPFILE=/tmp/tmpfile
        local PROGRESS=/tmp/tftp.progress
        local BYTES_LAST_CYCLE=0
        local BYTES_THIS_CYCLE=0

        rm -f ${PROGRESS}

        dd bs=$BLKSZ of=${TMPFILE} 2>&1 \
                | grep --line-buffered -E '[[:digit:]]* bytes' \
                | awk '{ print $1 }' >> ${PROGRESS} &

        # Loop while the 'dd' exists. It would be 'more better' if we
        # actually looked for the specific child ID of the running 
        # process by identifying which child process it was. If someone
        # else is running dd, it will mess things up.

        # My PID handling is dumb, it assumes you only have one running dd on
        # the system, this should be fixed to just get the PID of the child
        # process from the shell.

        while [ $(pidof dd) -gt 1 ]; do

                # PROTIP: You can sleep partial seconds (at least on linux)
                sleep .5    

                # Force dd to update us on it's progress (which gets
                # redirected to $PROGRESS file.
                # 
                # dumb pid handling again
                pkill -USR1 dd

                local BYTES_THIS_CYCLE=$(tail -1 $PROGRESS)
                local XFER_BLKS=$(((BYTES_THIS_CYCLE-BYTES_LAST_CYCLE)/BLKSZ))

                # Don't print anything unless we've got 1 block or more.
                # This allows for stdin/stderr interactions to occur
                # without printing a hash erroneously.

                # Also makes it possible for you to background 'scp',
                # but still use the /dev/stdout trick _even_ if scp
                # (inevitably) asks for a password. 
                #
                # Fancy!

                if [ $XFER_BLKS -gt 0 ]; then
                        printf "#%0.s" $(seq 0 $XFER_BLKS)
                        BYTES_LAST_CYCLE=$BYTES_THIS_CYCLE
                fi
        done

        local SIZE=$(stat -c"%s" $TMPFILE)
        local NOW=$(date +"%s")

        if [ $NOW -eq 0 ]; then
                NOW=1
        fi

        local DURATION=$(($NOW-$START))
        local BYTES_PER_SECOND=$(( SIZE / DURATION ))
        local KBPS=$((SIZE/DURATION/1024))
        local MD5=$(md5sum $TMPFILE | awk '{ print $1 }')

        # This function prints out ugly stuff suitable for eval() 
        # rather than a pretty string. This makes it a bit more 
        # flexible if you have a custom format (or dare I say, locale?)

        printf "\nDURATION=%d\nBYTES=%d\nKBPS=%f\nMD5=%s\n" \
            $DURATION \
            $SIZE \
            $KBPS \
            $MD5
}

Examples:

echo "wget"
wget -q -O /dev/stdout http://www.blah.com/somefile.zip | progress_filter

echo "tftp"
tftp -l /dev/stdout -g -r something/firmware.bin 192.168.1.1 | progress_filter

echo "scp"
scp user@192.168.1.1:~/myfile.tar /dev/stdout | progress_filter