mirror of https://github.com/tLDP/LDP
new
This commit is contained in:
gferg
parent
3078839a7e
commit
387372f731
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#!/bin/bash
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# badread.sh:
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# Attempting to use 'read'
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#+ to assign variables non-interactively.
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a=aaa
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b=bbb
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c=ccc
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echo "one two three" | read a b c
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# Try to reassign a, b, and c.
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echo "a = $a" # a = aaa
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echo "b = $b" # b = bbb
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echo "c = $c" # c = ccc
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# Reassignment failed.
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# ------------------------------
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# Try the following alternative.
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var=`echo "one two three"`
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set -- $var
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a=$1; b=$2; c=$3
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echo "-------"
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echo "a = $a" # a = one
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echo "b = $b" # b = two
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echo "c = $c" # c = three
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# Reassignment succeeded.
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exit 0
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#!/bin/bash
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# commentblock.sh
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: << COMMENTBLOCK
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echo "This line will not echo."
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This is a comment line missing the "#" prefix.
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This is another comment line missing the "#" prefix.
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&*@!!++=
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The above line will cause no error message,
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because the Bash interpreter will ignore it.
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COMMENTBLOCK
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echo "Exit value of above \"COMMENTBLOCK\" is $?." # 0
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# No error shown.
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# The above technique also comes in useful for commenting out
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#+ a block of working code for debugging purposes.
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# This saves having to put a "#" at the beginning of each line,
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#+ then having to go back and delete each "#" later.
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: << DEBUGXXX
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for file in *
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do
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cat "$file"
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done
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DEBUGXXX
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exit 0
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#!/bin/bash
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# Try the following when invoking this script.
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# sh ex33a -a
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# sh ex33a -abc
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# sh ex33a -a -b -c
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# sh ex33a -d
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# sh ex33a -dXYZ
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# sh ex33a -d XYZ
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# sh ex33a -abcd
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# sh ex33a -abcdZ
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# sh ex33a -z
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# sh ex33a a
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# Explain the results of each of the above.
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E_OPTERR=65
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if [ "$#" -eq 0 ]
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then # Script needs at least one command-line argument.
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echo "Usage $0 -[options a,b,c]"
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exit $E_OPTERR
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fi
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set -- `getopt "abcd:" "$@"`
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# Sets positional parameters to command-line arguments.
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# What happens if you use "$*" instead of "$@"?
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while [ ! -z "$1" ]
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do
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case "$1" in
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-a) echo "Option \"a\"";;
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-b) echo "Option \"b\"";;
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-c) echo "Option \"c\"";;
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-d) echo "Option \"d\" $2";;
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*) break;;
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esac
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shift
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done
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# It is better to use the 'getopts' builtin in a script,
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#+ rather than 'getopt'.
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# See "ex33.sh".
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exit 0
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#!/bin/bash
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# file-integrity.sh: Checking whether files in a given directory
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# have been tampered with.
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E_DIR_NOMATCH=70
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E_BAD_DBFILE=71
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dbfile=File_record.md5
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# Filename for storing records.
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set_up_database ()
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{
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echo ""$directory"" > "$dbfile"
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# Write directory name to first line of file.
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md5sum "$directory"/* >> "$dbfile"
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# Append md5 checksums and filenames.
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}
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check_database ()
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{
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local n=0
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local filename
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local checksum
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# ------------------------------------------- #
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# This file check should be unnecessary,
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#+ but better safe than sorry.
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if [ ! -r "$dbfile" ]
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then
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echo "Unable to read checksum database file!"
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exit $E_BAD_DBFILE
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fi
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# ------------------------------------------- #
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while read record[n]
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do
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directory_checked="${record[0]}"
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if [ "$directory_checked" != "$directory" ]
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then
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echo "Directories do not match up!"
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# Tried to use file for a different directory.
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exit $E_DIR_NOMATCH
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fi
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if [ "$n" -gt 0 ] # Not directory name.
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then
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filename[n]=$( echo ${record[$n]} | awk '{ print $2 }' )
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# md5sum writes records backwards,
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#+ checksum first, then filename.
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checksum[n]=$( md5sum "${filename[n]}" )
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if [ "${record[n]}" = "${checksum[n]}" ]
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then
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echo "${filename[n]} unchanged."
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else
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echo "${filename[n]} : CHECKSUM ERROR!"
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# File has been changed since last checked.
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fi
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fi
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let "n+=1"
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done <"$dbfile" # Read from checksum database file.
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}
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# =================================================== #
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# main ()
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if [ -z "$1" ]
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then
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directory="$PWD" # If not specified,
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else #+ use current working directory.
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directory="$1"
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fi
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clear # Clear screen.
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# ------------------------------------------------------------------ #
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if [ ! -r "$dbfile" ] # Need to create database file?
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then
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echo "Setting up database file, \""$directory"/"$dbfile"\"."; echo
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set_up_database
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fi
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# ------------------------------------------------------------------ #
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check_database # Do the actual work.
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echo
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# You may wish to redirect the stdout of this script to a file,
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#+ especially if the directory checked has many files in it.
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# For a much more thorough file integrity check,
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#+ consider the "Tripwire" package,
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#+ http://sourceforge.net/projects/tripwire/.
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exit 0
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#!/bin/bash
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# here-function.sh
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GetPersonalData ()
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{
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read firstname
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read lastname
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read address
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read city
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read state
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read zipcode
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} # This certainly looks like an interactive function, but...
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# Supply input to the above function.
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GetPersonalData <<RECORD001
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Bozo
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Bozeman
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2726 Nondescript Dr.
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Baltimore
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MD
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21226
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RECORD001
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echo
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echo "$firstname $lastname"
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echo "$address"
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echo "$city, $state $zipcode"
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echo
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exit 0
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#!/bin/bash
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# makedict.sh [make dictionary]
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# Modification of /usr/sbin/mkdict script.
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# Original script copyright 1993, by Alec Muffett.
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#
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# This modified script included in this document in a manner
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#+ consistent with the "LICENSE" document of the "Crack" package
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#+ that the original script is a part of.
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# This script processes text files to produce a sorted list
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#+ of words found in the files.
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# This may be useful for compiling dictionaries
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#+ and for lexicographic research.
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E_BADARGS=65
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if [ ! -r "$1" ] # Need at least one
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then #+ valid file argument.
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echo "Usage: $0 files-to-process"
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exit $E_BADARGS
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fi
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# SORT="sort" # No longer necessary to define options
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#+ to sort. Changed from original script.
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cat $* | # Contents of specified files to stdout.
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tr A-Z a-z | # Convert to uppercase.
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tr ' ' '\012' | # New: change spaces to newlines.
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# tr -cd '\012[a-z][0-9]' | # Get rid of everything non-alphanumeric
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#+ (original script).
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tr -c '\012a-z' '\012' | # Rather than deleting
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#+ now change non-alpha to newlines.
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sort | # $SORT options unnecessary now.
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uniq | # Remove duplicates.
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grep -v '^#' | # Delete lines beginning with a hashmark.
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grep -v '^$' # Delete blank lines.
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exit 0
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#!/bin/bash
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# pb.sh: phone book
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# Written by Rick Boivie, and used with permission.
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# Modifications by document author.
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MINARGS=1 # Script needs at least one argument.
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DATAFILE=./phonebook
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PROGNAME=$0
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E_NOARGS=70 # No arguments error.
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if [ $# -lt $MINARGS ]; then
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echo "Usage: "$PROGNAME" data"
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exit $E_NOARGS
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fi
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if [ $# -eq $MINARGS ]; then
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grep $1 "$DATAFILE"
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else
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( shift; "$PROGNAME" $* ) | grep $1
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# Script recursively calls itself.
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fi
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exit 0 # Script exits here.
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# It's o.k. to put non-hashmarked comments
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#+ and data after this point.
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# ------------------------------------------------------------------------
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# Sample "phonebook" datafile:
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John Doe 1555 Main St., Baltimore, MD 21228 (410) 222-3333
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Mary Moe 9899 Jones Blvd., Warren, NH 03787 (603) 898-3232
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Richard Roe 856 E. 7th St., New York, NY 10009 (212) 333-4567
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Sam Roe 956 E. 8th St., New York, NY 10009 (212) 444-5678
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Zoe Zenobia 4481 N. Baker St., San Franciso, SF 94338 (415) 501-1631
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# ------------------------------------------------------------------------
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$bash pb.sh Roe
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Richard Roe 856 E. 7th St., New York, NY 10009 (212) 333-4567
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Sam Roe 956 E. 8th St., New York, NY 10009 (212) 444-5678
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$bash pb.sh Roe Sam
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Sam Roe 956 E. 8th St., New York, NY 10009 (212) 444-5678
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# When more than one argument passed to script,
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#+ prints *only* the line(s) containing all the arguments.
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#!/bin/bash
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echo
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# -------------------------- #
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# First code block.
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echo -n "Enter a value: "
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read var
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echo "\"var\" = "$var""
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# Everything as expected here.
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# -------------------------- #
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echo
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echo -n "Enter another value: "
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read # No variable supplied for 'read', therefore...
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#+ Input to 'read' assigned to default variable, $REPLY.
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var="$REPLY"
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echo "\"var\" = "$var""
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# This is equivalent to the first code block.
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echo
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exit 0
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#!/bin/bash
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# reassign-stdout.sh
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LOGFILE=logfile.txt
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exec 6>&1 # Link file descriptor #6 with stdout.
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# Saves stdout.
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exec > $LOGFILE # stdout replaced with file "logfile.txt".
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# ----------------------------------------------------------- #
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# All output from commands in this block sent to file $LOGFILE.
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echo -n "Logfile: "
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date
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echo "-------------------------------------"
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echo
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echo "Output of \"ls -al\" command"
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echo
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ls -al
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echo; echo
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echo "Output of \"df\" command"
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echo
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df
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# ----------------------------------------------------------- #
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exec 1>&6 6>&- # Restore stdout and close file descriptor #6.
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echo
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echo "== stdout now restored to default == "
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echo
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ls -al
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echo
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exit 0
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#!/bin/bash
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# self-destruct.sh
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kill $$ # Script kills its own process here.
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# Recall that "$$" is the script's PID.
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echo "This line will not echo."
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# Instead, the shell sends a "Terminated" message to stdout.
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exit 0
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#!/bin/bash
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# self-document.sh: self-documenting script
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# Modification of "colm.sh".
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DOC_REQUEST=70
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if [ "$1" = "-h" -o "$1" = "--help" ] # Request help.
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then
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echo; echo "Usage: $0 [directory-name]"; echo
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cat "$0" | sed --silent -e '/DOCUMENTATIONXX$/,/^DOCUMENTATION/p' |
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sed -e '/DOCUMENTATIONXX/d'; exit $DOC_REQUEST; fi
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: << DOCUMENTATIONXX
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List the statistics of a specified directory in tabular format.
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---------------------------------------------------------------
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The command line parameter gives the directory to be listed.
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If no directory specified or directory specified cannot be read,
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then list the current working directory.
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DOCUMENTATIONXX
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if [ -z "$1" -o ! -r "$1" ]
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then
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directory=.
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||||
else
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directory="$1"
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||||
fi
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||||
echo "Listing of "$directory":"; echo
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(printf "PERMISSIONS LINKS OWNER GROUP SIZE MONTH DAY HH:MM PROG-NAME\n" \
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||||
; ls -l "$directory" | sed 1d) | column -t
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exit 0
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@ -0,0 +1,19 @@
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#!/bin/bash
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# self-exec.sh
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||||
echo
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||||
echo "This line appears ONCE in the script, yet it keeps echoing."
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||||
echo "The PID of this instance of the script is still $$."
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||||
# Demonstrates that a subshell is not forked off.
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||||
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||||
echo "==================== Hit Ctl-C to exit ===================="
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||||
sleep 1
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||||
exec $0 # Spawns another instance of this same script
|
||||
#+ that replaces the previous one.
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||||
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||||
echo "This line will never echo!" # Why not?
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||||
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||||
exit 0
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||||
|
|
@ -0,0 +1,37 @@
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|||
#!/bin/bash
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||||
variable="one two three four five"
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||||
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||||
set -- $variable
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||||
# Sets positional parameters to the contents of "$variable".
|
||||
|
||||
first_param=$1
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||||
second_param=$2
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||||
shift; shift # Shift past first two positional params.
|
||||
remaining_params="$*"
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||||
|
||||
echo
|
||||
echo "first parameter = $first_param" # one
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||||
echo "second parameter = $second_param" # two
|
||||
echo "remaining parameters = $remaining_params" # three four five
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||||
|
||||
echo; echo
|
||||
|
||||
# Again.
|
||||
set -- $variable
|
||||
first_param=$1
|
||||
second_param=$2
|
||||
echo "first parameter = $first_param" # one
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||||
echo "second parameter = $second_param" # two
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||||
|
||||
# ======================================================
|
||||
|
||||
set --
|
||||
# Unsets positional parameters if no variable specified.
|
||||
|
||||
first_param=$1
|
||||
second_param=$2
|
||||
echo "first parameter = $first_param" # (null value)
|
||||
echo "second parameter = $second_param" # (null value)
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||||
|
||||
exit 0
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||||
|
|
@ -0,0 +1,44 @@
|
|||
#!/bin/bash
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||||
# upperconv.sh
|
||||
# Converts a specified input file to uppercase.
|
||||
|
||||
E_FILE_ACCESS=70
|
||||
E_WRONG_ARGS=71
|
||||
|
||||
if [ ! -r "$1" ] # Is specified input file readable?
|
||||
then
|
||||
echo "Can't read from input file!"
|
||||
echo "Usage: $0 input-file output-file"
|
||||
exit $E_FILE_ACCESS
|
||||
fi # Will exit with same error
|
||||
#+ even if input file ($1) not specified.
|
||||
|
||||
if [ -z "$2" ]
|
||||
then
|
||||
echo "Need to specify output file."
|
||||
echo "Usage: $0 input-file output-file"
|
||||
exit $E_WRONG_ARGS
|
||||
fi
|
||||
|
||||
|
||||
exec 4<&0
|
||||
exec < $1 # Will read from input file.
|
||||
|
||||
exec 7>&1
|
||||
exec > $2 # Will write to output file.
|
||||
# Assumes output file writable (add check?).
|
||||
|
||||
# -----------------------------------------------
|
||||
cat - | tr a-z A-Z # Uppercase conversion.
|
||||
# ^^^^^ # Reads from stdin.
|
||||
# ^^^^^^^^^^ # Writes to stdout.
|
||||
# However, both stdin and stdout were redirected.
|
||||
# -----------------------------------------------
|
||||
|
||||
exec 1>&7 7>&- # Restore stout.
|
||||
exec 0<&4 4<&- # Restore stdin.
|
||||
|
||||
# After restoration, the following line prints to stdout as expected.
|
||||
echo "File \"$1\" written to \"$2\" as uppercase conversion."
|
||||
|
||||
exit 0
|
||||
Loading…
Reference in New Issue