Chapter 17. Here Documents

#!/bin/bash

# Non-interactive use of 'vi' to edit a file.
# Emulates 'sed'.

E_BADARGS=65

if [ -z "$1" ]
then
  echo "Usage: `basename $0` filename"
  exit $E_BADARGS
fi

TARGETFILE=$1

# Insert 2 lines in file, then save.
#--------Begin here document-----------#
vi $TARGETFILE <<x23LimitStringx23
i
This is line 1 of the example file.
This is line 2 of the example file.
^[
ZZ
x23LimitStringx23
#----------End here document-----------#

#  Note that ^[ above is a literal escape
#+ typed by Control-V <Esc>.

#  Bram Moolenaar points out that this may not work with 'vim',
#+ because of possible problems with terminal interaction.

exit 0

#!/bin/bash

wall <<zzz23EndOfMessagezzz23
E-mail your noontime orders for pizza to the system administrator.
    (Add an extra dollar for anchovy or mushroom topping.)
# Additional message text goes here.
# Note: Comment lines printed by 'wall'.
zzz23EndOfMessagezzz23

# Could have been done more efficiently by
#         wall <message-file
# However, saving a message template in a script saves work.

exit 0

#!/bin/bash

# 'echo' is fine for printing single line messages,
#  but somewhat problematic for for message blocks.
#  A 'cat' here document overcomes this limitation.

cat <<End-of-message
-------------------------------------
This is line 1 of the message.
This is line 2 of the message.
This is line 3 of the message.
This is line 4 of the message.
This is the last line of the message.
-------------------------------------
End-of-message

exit 0


#--------------------------------------------
# Code below disabled, due to "exit 0" above.

# S.C. points out that the following also works.
echo "-------------------------------------
This is line 1 of the message.
This is line 2 of the message.
This is line 3 of the message.
This is line 4 of the message.
This is the last line of the message.
-------------------------------------"
# However, text may not include double quotes unless they are escaped.

#!/bin/bash
# Same as previous example, but...

#  The - option to a here document <<-
#  suppresses tabs in the body of the document, but *not* spaces.

cat <<-ENDOFMESSAGE
	This is line 1 of the message.
	This is line 2 of the message.
	This is line 3 of the message.
	This is line 4 of the message.
	This is the last line of the message.
ENDOFMESSAGE
# The output of the script will be flush left.
# Leading tab in each line will not show.

# Above 5 lines of "message" prefaced by a tab, not spaces.
# Spaces not affected by   <<-  .


exit 0

#!/bin/bash
# Another 'cat' here document, using parameter substitution.

# Try it with no command line parameters,   ./scriptname
# Try it with one command line parameter,   ./scriptname Mortimer
# Try it with one two-word quoted command line parameter,
#                           ./scriptname "Mortimer Jones"

CMDLINEPARAM=1     # Expect at least command line parameter.

if [ $# -ge $CMDLINEPARAM ]
then
  NAME=$1          # If more than one command line param,
                   # then just take the first.
else
  NAME="John Doe"  # Default, if no command line parameter.
fi  

RESPONDENT="the author of this fine script"  
  

cat <<Endofmessage

Hello, there, $NAME.
Greetings to you, $NAME, from $RESPONDENT.

# This comment shows up in the output (why?).

Endofmessage

# Note that the blank lines show up in the output.
# So does the "comment".

exit 0

#!/bin/bash
#  A 'cat' here document, but with parameter substitution disabled.

NAME="John Doe"
RESPONDENT="the author of this fine script"  

cat <<'Endofmessage'

Hello, there, $NAME.
Greetings to you, $NAME, from $RESPONDENT.

Endofmessage

#  No parameter substitution when the "limit string" is quoted or escaped.
#  Either of the following at the head of the here document would have the same effect.
#  cat <<"Endofmessage"
#  cat <<\Endofmessage

exit 0

#!/bin/bash
# upload.sh

# Upload file pair (Filename.lsm, Filename.tar.gz)
# to incoming directory at Sunsite (metalab.unc.edu).

E_ARGERROR=65

if [ -z "$1" ]
then
  echo "Usage: `basename $0` filename"
  exit $E_ARGERROR
fi  


Filename=`basename $1`           # Strips pathname out of file name.

Server="metalab.unc.edu"
Directory="/incoming/Linux"
# These need not be hard-coded into script,
# but may instead be changed to command line argument.

Password="your.e-mail.address"   # Change above to suit.

ftp -n $Server <<End-Of-Session
# -n option disables auto-logon

user anonymous "$Password"
binary
bell                # Ring 'bell' after each file transfer
cd $Directory
put "$Filename.lsm"
put "$Filename.tar.gz"
bye
End-Of-Session

exit 0

#!/bin/bash
# here-function.sh

GetPersonalData ()
{
  read firstname
  read lastname
  read address
  read city 
  read state 
  read zipcode
} # This certainly looks like an interactive function, but...


# Supply input to the above function.
GetPersonalData <<RECORD001
Bozo
Bozeman
2726 Nondescript Dr.
Baltimore
MD
21226
RECORD001


echo
echo "$firstname $lastname"
echo "$address"
echo "$city, $state $zipcode"
echo

exit 0

#!/bin/bash

: <<TESTVARIABLES
${HOSTNAME?}${USER?}${MAIL?}  # Print error message if one of the variables not set.
TESTVARIABLES

exit 0

#!/bin/bash
# commentblock.sh

: << COMMENTBLOCK
echo "This line will not echo."
This is a comment line missing the "#" prefix.
This is another comment line missing the "#" prefix.

&*@!!++=
The above line will cause no error message,
because the Bash interpreter will ignore it.
COMMENTBLOCK

echo "Exit value of above \"COMMENTBLOCK\" is $?."   # 0
# No error shown.


#  The above technique also comes in useful for commenting out
#+ a block of working code for debugging purposes.
#  This saves having to put a "#" at the beginning of each line,
#+ then having to go back and delete each "#" later.

: << DEBUGXXX
for file in *
do
 cat "$file"
done
DEBUGXXX

exit 0

#!/bin/bash
# self-document.sh: self-documenting script
# Modification of "colm.sh".

DOC_REQUEST=70

if [ "$1" = "-h"  -o "$1" = "--help" ]     # Request help.
then
  echo; echo "Usage: $0 [directory-name]"; echo
  cat "$0" | sed --silent -e '/DOCUMENTATIONXX$/,/^DOCUMENTATION/p' |
  sed -e '/DOCUMENTATIONXX/d'; exit $DOC_REQUEST; fi

: << DOCUMENTATIONXX
List the statistics of a specified directory in tabular format.
---------------------------------------------------------------
The command line parameter gives the directory to be listed.
If no directory specified or directory specified cannot be read,
then list the current working directory.

DOCUMENTATIONXX

if [ -z "$1" -o ! -r "$1" ]
then
  directory=.
else
  directory="$1"
fi  

echo "Listing of "$directory":"; echo
(printf "PERMISSIONS LINKS OWNER GROUP SIZE MONTH DAY HH:MM PROG-NAME\n" \
; ls -l "$directory" | sed 1d) | column -t

exit 0