Мендель Купер - Искусство программирования на языке сценариев командной оболочки

Unless it is formatted:

inode permissions hard-links owner group ...

266705 crw-rw---- 1 root uucp

major minor day month date hh:mm:ss year path

4, 68 Sun Apr 20 09:27:33 2003 /dev/ttyS4

NOTE: that pesky comma after the major number

NOTE: the 'path' may be multiple fields:

/home/mszick/core

/proc/982/fd/0 -> /dev/null

/proc/982/fd/1 -> /home/mszick/.xsession-errors

/proc/982/fd/13 -> /tmp/tmpfZVVOCs (deleted)

/proc/982/fd/7 -> /tmp/kde-mszick/ksycoca

/proc/982/fd/8 -> socket:[11586]

/proc/982/fd/9 -> pipe:[11588]

If that isn't enough to keep your parser guessing,

either or both of the path components may be relative:

../Built-Shared -> Built-Static

../linux-2.4.20.tar.bz2 -> ../../../SRCS/linux-2.4.20.tar.bz2

The first character of the 11 (10?) character permissions field:

's' Socket

'd' Directory

'b' Block device

'c' Character device

'l' Symbolic link

NOTE: Hard links not marked - test for identical inode numbers

on identical filesystems.

All information about hard linked files are shared, except

for the names and the name's location in the directory system.

NOTE: A "Hard link" is known as a "File Alias" on some systems.

'-' An undistingushed file

Followed by three groups of letters for: User, Group, Others

Character 1: '-' Not readable; 'r' Readable

Character 2: '-' Not writable; 'w' Writable

Character 3, User and Group: Combined execute and special

'-' Not Executable, Not Special

'x' Executable, Not Special

's' Executable, Special

'S' Not Executable, Special

Character 3, Others: Combined execute and sticky (tacky?)

'-' Not Executable, Not Tacky

'x' Executable, Not Tacky

't' Executable, Tacky

'T' Not Executable, Tacky

Followed by an access indicator

Haven't tested this one, it may be the eleventh character

or it may generate another field

' ' No alternate access

'+' Alternate access

LSfieldsDoc

ListDirectory()

{

local -a T

local -i of=0 # Default return in variable

# OLD_IFS=$IFS # Using BASH default ' \t\n'

case "$#" in

3) case "$1" in

-of) of=1 ; shift ;;

* ) return 1 ;;

esac ;;

2) : ;; # Poor man's "continue"

*) return 1 ;;

esac

# NOTE: the (ls) command is NOT quoted (")

T=( $(ls --inode --ignore-backups --almost-all --directory \

--full-time --color=none --time=status --sort=none \

--format=long $1) )

case $of in

# Assign T back to the array whose name was passed as $2

0) eval $2=\( \"\$\{T\[@\]\}\" \) ;;

# Write T into filename passed as $2

1) echo "${T[@]}" > "$2" ;;

esac

return 0

}

# # # # # Is that string a legal number? # # # # #

#

# IsNumber "Var"

# # # # # There has to be a better way, sigh...

IsNumber()

{

local -i int

if [ $# -eq 0 ]

then

return 1

else

(let int=$1) 2>/dev/null

return $? # Exit status of the let thread

fi

}

# # # # # Index Filesystem Directory Information # # # # #

#

# IndexList "Field-Array-Name" "Index-Array-Name"

# or

# IndexList -if Field-Array-Filename Index-Array-Name

# IndexList -of Field-Array-Name Index-Array-Filename

# IndexList -if -of Field-Array-Filename Index-Array-Filename

# # # # #

: << IndexListDoc

Walk an array of directory fields produced by ListDirectory

Having suppressed the line breaks in an otherwise line oriented

report, build an index to the array element which starts each line.

Each line gets two index entries, the first element of each line

(inode) and the element that holds the pathname of the file.

The first index entry pair (Line-Number==0) are informational:

Index-Array-Name[0] : Number of "Lines" indexed

Index-Array-Name[1] : "Current Line" pointer into Index-Array-Name

The following index pairs (if any) hold element indexes into

the Field-Array-Name per:

Index-Array-Name[Line-Number * 2] : The "inode" field element.

NOTE: This distance may be either +11 or +12 elements.

Index-Array-Name[(Line-Number * 2) + 1] : The "pathname" element.

NOTE: This distance may be a variable number of elements.

Next line index pair for Line-Number+1.

IndexListDoc

IndexList()

{

local -a LIST # Local of listname passed

local -a -i INDEX=( 0 0 ) # Local of index to return

local -i Lidx Lcnt

local -i if=0 of=0 # Default to variable names

case "$#" in # Simplistic option testing

0) return 1 ;;

1) return 1 ;;

2) : ;; # Poor man's continue

3) case "$1" in

-if) if=1 ;;

-of) of=1 ;;

* ) return 1 ;;

esac ; shift ;;

4) if=1 ; of=1 ; shift ; shift ;;

*) return 1

esac

# Make local copy of list

case "$if" in

0) eval LIST=\( \"\$\{$1\[@\]\}\" \) ;;

1) LIST=( $(cat $1) ) ;;

esac

# Grok (grope?) the array

Lcnt=${#LIST[@]}

Lidx=0

until (( Lidx >= Lcnt ))

do

if IsNumber ${LIST[$Lidx]}

then

local -i inode name

local ft

inode=Lidx

local m=${LIST[$Lidx+2]} # Hard Links field

ft=${LIST[$Lidx+1]:0:1} # Fast-Stat

case $ft in

b) ((Lidx+=12)) ;; # Block device

c) ((Lidx+=12)) ;; # Character device

*) ((Lidx+=11)) ;; # Anything else

esac

name=Lidx

case $ft in

-) ((Lidx+=1)) ;; # The easy one

b) ((Lidx+=1)) ;; # Block device

c) ((Lidx+=1)) ;; # Character device

d) ((Lidx+=1)) ;; # The other easy one

l) ((Lidx+=3)) ;; # At LEAST two more fields

# A little more elegance here would handle pipes,

#+ sockets, deleted files - later.

*) until IsNumber ${LIST[$Lidx]} || ((Lidx >= Lcnt))

do

((Lidx+=1))

done

;; # Not required

esac

INDEX[${#INDEX[*]}]=$inode

INDEX[${#INDEX[*]}]=$name

INDEX[0]=${INDEX[0]}+1 # One more "line" found

# echo "Line: ${INDEX[0]} Type: $ft Links: $m Inode: \

# ${LIST[$inode]} Name: ${LIST[$name]}"

else

((Lidx+=1))

fi

done

case "$of" in

0) eval $2=\( \"\$\{INDEX\[@\]\}\" \) ;;

1) echo "${INDEX[@]}" > "$2" ;;

esac

return 0 # What could go wrong?

}

# # # # # Content Identify File # # # # #

#

# DigestFile Input-Array-Name Digest-Array-Name

# or

# DigestFile -if Input-FileName Digest-Array-Name

# # # # #

# Here document used as a comment block.

: <

The key (no pun intended) to a Unified Content File System (UCFS)

is to distinguish the files in the system based on their content.

Distinguishing files by their name is just, so, 20th Century.

The content is distinguished by computing a checksum of that content.

This version uses the md5sum program to generate a 128 bit checksum

representative of the file's contents.

There is a chance that two files having different content might

generate the same checksum using md5sum (or any checksum). Should

that become a problem, then the use of md5sum can be replace by a

cyrptographic signature. But until then...

The md5sum program is documented as outputting three fields (and it

does), but when read it appears as two fields (array elements). This

is caused by the lack of whitespace between the second and third field.

So this function gropes the md5sum output and returns:

[0] 32 character checksum in hexidecimal (UCFS filename)

[1] Single character: ' ' text file, '*' binary file

[2] Filesystem (20th Century Style) name