new

LDP/guide/docbook/abs-guide/Draw-box.sh

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+#!/bin/bash
+# Draw-box.sh: Drawing a box using ASCII characters.
+
+# Script by Stefano Palmeri, with minor editing by document author.
+# Used in the "ABS Guide" with permission.
+
+
+######################################################################
+###  draw_box function doc  ###
+
+#  The "draw_box" function lets the user
+#+ draw a box into a terminal.       
+#
+#  Usage: draw_box ROW COLUMN HEIGHT WIDTH [COLOR] 
+#  ROW and COLUMN represent the position        
+#+ of the upper left angle of the box you're going to draw.
+#  ROW and COLUMN must be greater than 0
+#+ and less than current terminal dimension.
+#  HEIGHT is the number of rows of the box, and must be > 0. 
+#  HEIGHT + ROW must be <= than current terminal height. 
+#  WIDTH is the number of columns of the box and must be > 0.
+#  WIDTH + COLUMN must be <= than current terminal width.
+#
+# E.g.: If your terminal dimension is 20x80,
+#  draw_box 2 3 10 45 is good
+#  draw_box 2 3 19 45 has bad HEIGHT value (19+2 > 20)
+#  draw_box 2 3 18 78 has bad WIDTH value (78+3 > 80)
+#
+#  COLOR is the color of the box frame.
+#  This is the 5th argument and is optional.
+#  0=black 1=red 2=green 3=tan 4=blue 5=purple 6=cyan 7=white.
+#  If you pass the function bad arguments,
+#+ it will just exit with code 65,
+#+ and no messages will be printed on stderr.
+#
+#  Clear the terminal before you start to draw a box.
+#  The clear command is not contained within the function.
+#  This allows the user to draw multiple boxes, even overlapping ones.
+
+###  end of draw_box function doc  ### 
+######################################################################
+
+draw_box(){
+
+#=============#
+HORZ="-"
+VERT="|"
+CORNER_CHAR="+"
+
+MINARGS=4
+E_BADARGS=65
+#=============#
+
+
+if [ $# -lt "$MINARGS" ]; then                 # If args are less than 4, exit.
+    exit $E_BADARGS
+fi
+
+# Looking for non digit chars in arguments.
+# Probably it could be done better (exercise for the reader?).
+if echo $@ | tr -d [:blank:] | tr -d [:digit:] | grep . &> /dev/null; then
+   exit $E_BADARGS
+fi
+
+BOX_HEIGHT=`expr $3 - 1`   #  -1 correction needed because angle char "+" is 
+BOX_WIDTH=`expr $4 - 1`    #+ a part of both box height and width.
+T_ROWS=`tput lines`        #  Define current terminal dimension 
+T_COLS=`tput cols`         #+ in rows and columns.
+         
+if [ $1 -lt 1 ] || [ $1 -gt $T_ROWS ]; then    #  Start checking if arguments
+   exit $E_BADARGS                             #+ are correct.
+fi
+if [ $2 -lt 1 ] || [ $2 -gt $T_COLS ]; then
+   exit $E_BADARGS
+fi
+if [ `expr $1 + $BOX_HEIGHT + 1` -gt $T_ROWS ]; then
+   exit $E_BADARGS
+fi
+if [ `expr $2 + $BOX_WIDTH + 1` -gt $T_COLS ]; then
+   exit $E_BADARGS
+fi
+if [ $3 -lt 1 ] || [ $4 -lt 1 ]; then
+   exit $E_BADARGS
+fi                                 # End checking arguments.
+
+plot_char(){                       # Function within a function.
+   echo -e "\E[${1};${2}H"$3
+}
+
+echo -ne "\E[3${5}m"               # Set box frame color, if defined.
+
+# start drawing the box
+
+count=1                                         #  Draw vertical lines using
+for (( r=$1; count<=$BOX_HEIGHT; r++)); do      #+ plot_char function.
+  plot_char $r $2 $VERT
+  let count=count+1
+done 
+
+count=1
+c=`expr $2 + $BOX_WIDTH`
+for (( r=$1; count<=$BOX_HEIGHT; r++)); do
+  plot_char $r $c $VERT
+  let count=count+1
+done 
+
+count=1                                        #  Draw horizontal lines using
+for (( c=$2; count<=$BOX_WIDTH; c++)); do      #+ plot_char function.
+  plot_char $1 $c $HORZ
+  let count=count+1
+done 
+
+count=1
+r=`expr $1 + $BOX_HEIGHT`
+for (( c=$2; count<=$BOX_WIDTH; c++)); do
+  plot_char $r $c $HORZ
+  let count=count+1
+done 
+
+plot_char $1 $2 $CORNER_CHAR                   # Draw box angles.
+plot_char $1 `expr $2 + $BOX_WIDTH` +
+plot_char `expr $1 + $BOX_HEIGHT` $2 +
+plot_char `expr $1 + $BOX_HEIGHT` `expr $2 + $BOX_WIDTH` +
+
+echo -ne "\E[0m"             #  Restore old colors.
+
+P_ROWS=`expr $T_ROWS - 1`    #  Put the prompt at bottom of the terminal.
+
+echo -e "\E[${P_ROWS};1H"
+}      
+
+
+# Now, let's try drawing a box.
+clear                       # Clear the terminal.
+R=2      # Row
+C=3      # Column
+H=10     # Height
+W=45     # Width 
+col=1    # Color (red)
+draw_box $R $C $H $W $col   # Draw the box.
+
+exit 0
+
+# Exercise:
+# --------
+# Add the option of printing text within the drawn box.

LDP/guide/docbook/abs-guide/avoid-subshell.sh

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+#!/bin/bash
+# avoid-subshell.sh
+# Suggested by Matthew Walker.
+
+Lines=0
+
+echo
+
+cat myfile.txt | while read line;
+                 do {
+                   echo $line
+                   (( Lines++ ));  #  Incremented values of this variable
+                                   #+ inaccessible outside loop.
+                                   #  Subshell problem.
+                 }
+                 done
+
+echo "Number of lines read = $Lines"     # 0
+                                         # Wrong!
+
+echo "------------------------"
+
+
+exec 3<> myfile.txt
+while read line <&3
+do {
+  echo "$line"
+  (( Lines++ ));                   #  Incremented values of this variable
+                                   #+ accessible outside loop.
+                                   #  No subshell, no problem.
+}
+done
+exec 3>&-
+
+echo "Number of lines read = $Lines"     # 8
+
+echo
+
+exit 0
+
+# Lines below not seen by script.
+
+$ cat myfile.txt
+
+Line 1.
+Line 2.
+Line 3.
+Line 4.
+Line 5.
+Line 6.
+Line 7.
+Line 8.

LDP/guide/docbook/abs-guide/is-spammer.sh

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+#! /bin/bash
+# is-spammer.sh: Identifying spam domains
+#
+#  This is a simplified version of the "is_spammer.bash
+#+ script in the Contributed Scripts appendix.
+
+# is-spammer <domain.name>
+# $Id$
+
+# Uses an external program: 'dig'
+# Tested with version: 9.2.4rc5
+
+# Uses functions.
+# Uses IFS to parse strings by assignment into arrays.
+# And even does something useful: checks e-mail blacklists.
+
+# Use the domain.name(s) from the text body:
+# http://www.good_stuff.spammer.biz/just_ignore_everything_else
+#                       ^^^^^^^^^^^
+# Or the domain.name(s) from any e-mail address:
+# Really_Good_Offer@spammer.biz
+#                   ^^^^^^^^^^^
+# as the only argument to this script.
+#(PS: have your Inet connection running)
+#
+# So, to invoke this script in the above two instances:
+#       is-spammer.sh spammer.biz
+
+
+# Whitespace == :Space:Tab:Line Feed:Carriage Return:
+WSP_IFS=$'\x20'$'\x09'$'\x0A'$'\x0D'
+
+# No Whitespace == Line Feed:Carriage Return
+No_WSP=$'\x0A'$'\x0D'
+
+# Field separator for dotted decimal ip addresses
+ADR_IFS=${No_WSP}'.'
+
+# Get the dns text resource record
+# get_txt <error_code> <list_query>
+get_txt() {
+
+    # parse $1 by assignment at the dots
+    local -a dns
+    IFS=$ADR_IFS
+    dns=( $1 )
+    IFS=$WSP_IFS
+    if [ "${dns[0]}" == '127' ]
+    then
+        # see if there is a reason
+        echo $(dig +short $2 -t txt)
+    fi
+}
+
+# Get the dns address resource record
+# chk_adr <rev_dns> <list_server>
+chk_adr() {
+    local reply
+    local server
+    local reason
+
+    server=${1}${2}
+    reply=$( dig +short ${server} )
+
+    # if reply might be an error code . . .
+    if [ ${#reply} -gt 6 ]
+    then
+        reason=$(get_txt ${reply} ${server} )
+        reason=${reason:-${reply}}
+    fi
+    echo ${reason:-' not blacklisted.'}
+}
+
+# Need to get the IP address from the name.
+echo 'Get address of: '$1
+ip_adr=$(dig +short $1)
+dns_reply=${ip_adr:-' no answer '}
+echo ' Found address: '${dns_reply}
+
+# A valid reply is at least 4 digits plus 3 dots.
+if [ ${#ip_adr} -gt 6 ]
+then
+    echo
+    declare query
+
+    # Parse by assignment at the dots.
+    declare -a dns
+    IFS=$ADR_IFS
+    dns=( ${ip_adr} )
+    IFS=$WSP_IFS
+
+    # Reorder octets into dns query order.
+    rev_dns="${dns[3]}"'.'"${dns[2]}"'.'"${dns[1]}"'.'"${dns[0]}"'.'
+
+# See: http://www.spamhaus.org (Conservative, well maintained)
+    echo -n 'spamhaus.org says: '
+    echo $(chk_adr ${rev_dns} 'sbl-xbl.spamhaus.org')
+
+# See: http://ordb.org (Open mail relays)
+    echo -n '   ordb.org  says: '
+    echo $(chk_adr ${rev_dns} 'relays.ordb.org')
+
+# See: http://www.spamcop.net/ (You can report spammers here)
+    echo -n ' spamcop.net says: '
+    echo $(chk_adr ${rev_dns} 'bl.spamcop.net')
+
+# # # other blacklist operations # # #
+
+# See: http://cbl.abuseat.org.
+    echo -n ' abuseat.org says: '
+    echo $(chk_adr ${rev_dns} 'cbl.abuseat.org')
+
+# See: http://dsbl.org/usage (Various mail relays)
+    echo
+    echo 'Distributed Server Listings'
+    echo -n '       list.dsbl.org says: '
+    echo $(chk_adr ${rev_dns} 'list.dsbl.org')
+
+    echo -n '   multihop.dsbl.org says: '
+    echo $(chk_adr ${rev_dns} 'multihop.dsbl.org')
+
+    echo -n 'unconfirmed.dsbl.org says: '
+    echo $(chk_adr ${rev_dns} 'unconfirmed.dsbl.org')
+
+else
+    echo
+    echo 'Could not use that address.'
+fi
+
+exit 0
+
+# Exercises:
+# --------
+
+# 1) Check arguments to script,
+#    and exit with appropriate error message if necessary.
+
+# 2) Check if on-line at invocation of script,
+#    and exit with appropriate error message if necessary.
+
+# 3) Substitute generic variables for "hard-coded" BHL domains.
+
+# 4) Set a time-out for the script using the "+time=" option
+     to the 'dig' command.

LDP/guide/docbook/abs-guide/prepend.sh

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+#!/bin/bash
+# prepend.sh: Add text at beginning of file.
+#
+#  Example contributed by Kenny Stauffer,
+#  and slightly modified by document author.
+
+
+E_NOSUCHFILE=65
+
+read -p "File: " file   # -p arg to 'read' displays prompt.
+if [ ! -e "$file" ]
+then   # Bail out if no such file.
+  echo "File $file not found."
+  exit $E_NOSUCHFILE
+fi
+
+read -p "Title: " title
+cat - $file <<<$title > $file.new
+
+echo "Modified file is $file.new"
+
+exit 0
+
+# from "man bash"
+# Here Strings
+# 	A variant of here documents, the format is:
+# 
+# 		<<<word
+# 
+# 	The word is expanded and supplied to the command on its standard input.

LDP/guide/docbook/abs-guide/remote.bash

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+#!/bin/bash
+# remote.bash: Using ssh.
+
+# This example by Michael Zick.
+# Used with permission.
+
+
+#   Presumptions:
+#   ------------
+#   fd-2 isn't being captured ( '2>/dev/null' ).
+#   ssh/sshd presumes stderr ('2') will display to user.
+#
+#   sshd is running on your machine.
+#   For any 'standard' distribution, it probably is,
+#+  and without any funky ssh-keygen having been done.
+
+# Try ssh to your machine from the command line:
+#
+# $ ssh $HOSTNAME
+# Without extra set-up you'll be asked for your password.
+#   enter password
+#   when done,  $ exit
+#
+# Did that work? If so, you're ready for more fun.
+
+# Try ssh to your machine as 'root':
+#
+#   $  ssh -l root $HOSTNAME
+#   When asked for password, enter root's, not yours.
+#          Last login: Tue Aug 10 20:25:49 2004 from localhost.localdomain
+#   Enter 'exit' when done.
+
+#  The above gives you an interactive shell.
+#  It is possible for sshd to be set up in a 'single command' mode,
+#+ but that is beyond the scope of this example.
+#  The only thing to note is that the following will work in
+#+ 'single command' mode.
+
+
+# A basic, write stdout (local) command.
+
+ls -l
+
+# Now the same basic command on a remote machine.
+# Pass a different 'USERNAME' 'HOSTNAME' if desired:
+USER=${USERNAME:-$(whoami)}
+HOST=${HOSTNAME:-$(hostname)}
+
+#  Now excute the above command line on the remote host,
+#+ with all transmissions encrypted.
+
+ssh -l ${USER} ${HOST} " ls -l "
+
+#  The expected result is a listing of your username's home
+#+ directory on the remote machine.
+#  To see any difference, run this script from somewhere
+#+ other than your home directory.
+
+#  In other words, the Bash command is passed as a quoted line
+#+ to the remote shell, which executes it on the remote machine.
+#  In this case, sshd does  ' bash -c "ls -l" '   on your behalf.
+
+#  For information on topics such as not having to enter a
+#+ password/passphrase for every command line, see
+#+    man ssh
+#+    man ssh-keygen
+#+    man sshd_config.
+
+exit 0