2745.html

<h3>Errata</h3>
<h1>Shell Scripting Recipes</h1>
<h2>A Problem-Solution Approach</h2>
<h3>by Chris F.A. Johnson</h3>

<h2>Chapter 1</h2>
<h4>standard-vars</h4>
<p>
  <b>Page 9</b><br>
  For the sake of consistency with the code that supposedly created
  the file, the lines from "standard-vars" should read:
<pre>
NL="
"
"R="
TAB="   "
</pre>
<h4>Bourne Shell Expansions</h4>
<p>
   A number of newlines are missing from this section, starting with
   the last line of <b>Page 12</b> which should be:
<pre>
$ echo /$var-y/
/y/
</pre>
  <b>Page 13</b><br>
<pre>
$ echo /${var+C}/
/X/

  Finally, when the variable is set and not null, VALUE is used, with
or without the colon.

$ var=A
$ echo /${var:+X}/
/X/
$ echo /${var+X}/
/X/
</pre>
  An extra comma appears on <b>Page 14</b>; it should be:
<pre>
>    list=${list:+$list,}$f
</pre>
<p>Thanks to Jens Schweikhardt for pointing out the errors in Chapter 1.</p>

<h2>Chapter 3</h2>
<h4>Notes: gsub()</h4>
<p>On <b>Page 72</b> the '_gsub' function under "Notes" should be:</p>
<pre>
_gsub() { _GSUB=${1//"$2"/"$3"}; }
</pre>

<h2>Chapter 5</h2>
<h4>3. Convert Degrees Celsius to Fahrenheit</h4>
<b>Page 126</b>, in the c2f (not '_c2f') function, '_C2F=' should be
removed:
<pre>
c2f()
{
    prompt="Degrees Celsius" arg "$@"
    echo "$arg" |
        awk '{
               printf "%" pr "f\n", $1 * 1.8 + 32
             }' pr=${precision:-.2}
}
</pre>

<p><b>Page 129</b>, in the cm2i (not '_cm2i') function, 'Millimeters'
should be 'Centimeters', and the function call and variable in the
last two lines of 'mm2i' are wrong.</p>
<pre>
cm2i()
{
    units=inches
    prompt=Centimeters arg "$@"
    _cm2i "$arg"
    printf "%s%s\n" "$_CM2I" "${units:+ $units}"
}
</pre>

<p><b>Convert Millimeters to Inches</b>
<pre>
mm2i()
{
    units=inches
    prompt=Millimeters arg "$@"
    _mm2i "$arg"
    printf "%s%s\n" "$_MM2I" "${units:+ $units}"
}
</pre>

<h4>The Lengths and Distances Menu</h4>
<p><b>Page 134</b>, the last item on the menu should be:
<pre>
     8. mm2i - millimeters to inches
</pre>
<p>David Emme provided the corrections to Chapter 5; thanks, David.</p>

<h2>Chapter 15</h2>
<h4>_put_csv</h4>

<p>On <b>Page 312</b>, the '_put_csv' function didn't deal with leading
null fields. Gregg Nelson provided a fix:
<pre>
_put_csv()
{
    _PUT_CSV=
    for field in "$@"  ## loop through the fields (on command line)
    do
      case $field in
         ## If field contains non-numerics, enclose in quotes
         *[!0-9.-]*) _PUT_CSV=$_PUT_CSV\"$field\",
                     ;;
         '') _PUT_CSV=$_PUT_CSV,
             ;;
         *) _PUT_CSV=$_PUT_CSV$field,
           ;;
      esac
    done
    _PUT_CSV=${_PUT_CSV%,}     ## remove trailing comma
}
</pre>

<h2>Chapter 20</h2>
<p>In the install_script() function on <b>Page 402</b>, the variable
'$file' should be '$1', and the path should be removed:
<pre>
    filename=${1%$devel_suffix}               ## Command name, without suffix
    filename=${filename##*/}                  ## Remove path; use file name alone
</pre>

<p>Also in the install_script() function, on <b>Page 403</b>, removing
write permissions from the script can cause problems in some
instances. If they do, just remove them or comment them out:
<pre>
#      ## Remove write permissions
#      chmod +rx,-w "$dest"
</pre>

<h4>_uniqfile()</h4>
<p>A function was missing from the cpsh script on <b>Page 403</b>.
This should be inserted before "progname=${0##*/}".
<pre>
_uniqfile()
{
    _base=$1
    _n=1
    while [ -f "$_UNIQFILE" ] || [ -d "$_UNIQFILE" ]
    do
      _zpad $_n ${VERSION_WIDTH}
      _UNIQFILE=$_base-$_ZPAD
      _n=$(( $_n + 1 ))
    done
}
</pre>