Tcl/Tk GUI for sha1sum

TkSHA1.sh

#!/bin/sh
#\
exec wish "$0" "$@"

wm title . "sha1sum front-end"

for {set i 0} {$i < $argc} {incr i} {
    set file [lindex $argv $i]
    # label ".lab$i" -text "Computing SHA1 of $file..."
    global "var$i"
    set "var$i" "Computing SHA1 of $file..."
    entry ".lab$i" -state readonly -textvariable "var$i" -width [string length [set "var$i"]]
    pack ".lab$i" -fill x -side top

    set io "sha1io$i"
    set $io [open "|sha1sum $file" r]

    fconfigure [set $io] -blocking false

    set update_code "
        global var$i
        # puts \"Update\"
        set read \[gets [set $io] sha1\]
        # puts \$read
        if {\$read > 0} {
            # puts \"\$sha1\"
            # .lab$i configure -text \"\$sha1\"
            set var$i \"\$sha1\"
            .lab$i configure -width \$read
        } else {
            after 100 update$i
        }
    "

    # puts $update_code

    proc "update$i" {} $update_code

    after 100 "update$i"
}

Designed to be a Nautilus script ($HOME/.local/share/nautilus/scripts).
It can be applied to set of selected files.