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Making a Simple Front-End to the Wget Command Using Korn Shell

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RedCreator37
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3 min read

In the previous post we made a simple Hello World script using the Common Desktop Environment's Korn shell (dtksh). This time we're going to make a front-end to the ubiquitous wget command.

You probably know what wget is, tl;dr it's a program for retrieving files from the internet. It's present on most Linux and BSD systems.

As the front-end is going to be very simple, we'll need just 6 controls on the main window. A URL entry field, an output path field, two labels to describe them, a button and a checkbox to download into an existing file (the -c switch).

First we need to tell the shell to use dtksh:

#!/usr/dt/bin/dtksh
. /usr/dt/lib/dtksh/DtFuncs.dtsh

...and we need to write the functions which will be trigerred by the buttons:

startDownload() {
  XmTextFieldGetString URL $URLFIELD
  XmTextFieldGetString OUTPATH $OUTFIELD
  CMD="wget $URL -O $OUTFIELD"

  # append "-c" when "continue downloading" is checked
  if XmToggleButtonGetState $DOCONTINUE; then
    CMD=$CMD" -c"
  fi
  reportStatus
}

reportStatus() {
  # the following line opens a terminal window and runs the command
  /usr/dt/bin/dtterm -title "Retrieve file" -e $CMD

  DtkshDisplayInformationDialog "Download a file" \
    "Downloading from
$URL
done."
}

The first function (startDownload) gets the URL and output path and constructs the full command. The if statement appends -c to the command when the "continue downloading" checkbox is checked.

The second opens a dtterm (CDE's terminal emulator) and runs the command. It shows an info window when the download is completed.

We now have to define the UI. As mentioned, we need a window, a control pane in it, two labels and two fields, a toggle button (checkbox) and a button to start the download.

XtInitialize TOPLEVEL wgetcde Dtksh $0
XtSetValues $TOPLEVEL title:"Download a file"

XtCreateManagedWidget BBOARD bboard XmBulletinBoard $TOPLEVEL \
  resizePolicy:RESIZE_NONE height:170 width:400

XtCreateManagedWidget LABEL1 label1 XmLabel $BBOARD \
  labelString:"File URL:"

XtCreateManagedWidget URLFIELD urlfield XmTextField $BBOARD \
  width:380 x:10 y:35

XtCreateManagedWidget LABEL2 label2 XmLabel $BBOARD \
  labelString:"Output path (include the filename)" \
  x:10 y:70

XtCreateManagedWidget OUTFIELD outfield XmTextField $BBOARD \
  width:380 x:10 y:95

XtCreateManagedWidget DOCONTINUE docontinue XmToggleButton $BBOARD \
  labelString:"Continue downloading an existing file" \
  x:10 y:130

XtCreateManagedWidget BUTTON startbutton XmPushButton $BBOARD \
  labelString:"START" \
  height:27 width:100 x:290 y:130

We can also put some placeholder values in the text fields to aid the user:

XmTextFieldSetString $OUTFIELD "~/"
XmTextFieldSetString $URLFIELD "https://"

...and we have to bind our startDownload function to the button:

XtAddCallback $BUTTON activateCallback startDownload

All that's left is displaying the window:

XtRealizeWidget $TOPLEVEL
XtMainLoop

If you try to run the script now, you should get something similar to this:

The finished front-end to the wget command

Here's a quick list of ideas to improve it:

  • redirect the output to another window instead of using dtterm
  • display an error / warning popup on errors
  • support more download options
  • close the main window automatically when the download finishes.

Here's the full script:

#!/usr/dt/bin/dtksh
. /usr/dt/lib/dtksh/DtFuncs.dtsh

startDownload() {
  XmTextFieldGetString URL $URLFIELD
  XmTextFieldGetString OUTPATH $OUTFIELD
  CMD="wget $URL -O $OUTFIELD"

  # append "-c" when "continue downloading" is checked
  if XmToggleButtonGetState $DOCONTINUE; then
    CMD=$CMD" -c"
  fi
  reportStatus
}

reportStatus() {
  # the following line opens a terminal window and runs the command
  /usr/dt/bin/dtterm -title "Retrieve file" -e $CMD

  DtkshDisplayInformationDialog "Download a file" \
    "Downloading from
$URL
done."
}

####################################################################
XtInitialize TOPLEVEL wgetcde Dtksh $0
XtSetValues $TOPLEVEL title:"Download a file"

XtCreateManagedWidget BBOARD bboard XmBulletinBoard $TOPLEVEL \
  resizePolicy:RESIZE_NONE height:170 width:400

XtCreateManagedWidget LABEL1 label1 XmLabel $BBOARD \
  labelString:"File URL:"

XtCreateManagedWidget URLFIELD urlfield XmTextField $BBOARD \
  width:380 x:10 y:35

XtCreateManagedWidget LABEL2 label2 XmLabel $BBOARD \
  labelString:"Output path (include the filename)" \
  x:10 y:70

XtCreateManagedWidget OUTFIELD outfield XmTextField $BBOARD \
  width:380 x:10 y:95

XtCreateManagedWidget DOCONTINUE docontinue XmToggleButton $BBOARD \
  labelString:"Continue downloading an existing file" \
  x:10 y:130

XtCreateManagedWidget BUTTON startbutton XmPushButton $BBOARD \
  labelString:"START" \
  height:27 width:100 x:290 y:130

####################################################################
XmTextFieldSetString $OUTFIELD "~/"
XmTextFieldSetString $URLFIELD "http://"
XtAddCallback $BUTTON activateCallback startDownload

####################################################################
XtRealizeWidget $TOPLEVEL
XtMainLoop
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