以KSH為例 : ?



# !/usr/bin/ksh
#
#?SCRIPT:?12_ways_to_parse.ksh.ksh
#
#
#?REV:?1.2.A
#
#?PURPOSE:??This?script?shows?the?different?ways?of?reading
#???????a?file?line?by?line.??Again?there?is?not?just?one?way
#???????to?read?a?file?line?by?line?and?some?are?faster?than
#???????others?and?some?are?more?intuitive?than?others.
#
#?REV?LIST:
#
#???????03/15/2002?-?Randy?Michael
#???????Set?each?of?the?while?loops?up?as?functions?and?the?timing
#???????of?each?function?to?see?which?one?is?the?fastest.
#
#######################################################################
#
#???????NOTE:?To?output?the?timing?to?a?file?use?the?following?syntax:
#
#??????????12_ways_to_parse.ksh?file_to_process??>?output_file_name?2>&1
#
#???????The?actaul?timing?data?is?sent?to?standard?error,?file?
#???????descriptor?(2),?and?the?function?name?header?is?sent
#???????to?standard?output,?file?descriptor?(1).
#
#######################################################################
#
#?set?-n??#?Uncomment?to?check?command?syntax?without?any?execution
#?set?-x??#?Uncomment?to?debug?this?script
#

FILENAME = " $1 "
TIMEFILE = " /tmp/loopfile.out "
> $TIMEFILE
THIS_SCRIPT = $(basename?$ 0 )

# #####################################
function?usage
{
echo? " /nUSAGE:?$THIS_SCRIPT??file_to_process/n "
echo? " OR?-?To?send?the?output?to?a?file?use:? "
echo? " /n$THIS_SCRIPT??file_to_process??>?output_file_name?2>&1?/n "
exit ? 1
}
# #####################################
function?while_read_LINE
{
cat? $FILENAME ? | ? while ? read ?LINE
do
????????echo? " $LINE "
???????? :
done
}
# #####################################
function?while_read_LINE_bottom?
{
while ? read ?LINE
do
????????echo? " $LINE "
???????? :

done? < ? $FILENAME
}
# #####################################
function?while_line_LINE_bottom
{
while ?line?LINE
do
????????echo? $LINE
???????? :
done? < ? $FILENAME
}
# #####################################
function?cat_while_LINE_line??
{
cat? $FILENAME ? | ? while ?LINE = `line`
do
????????echo? " $LINE "
???????? :
done
}
# #####################################
function?while_line_LINE
{
cat? $FILENAME ? | ? while ?line?LINE
do
????????echo? " $LINE "
???????? :
done
}
# #####################################
function?while_LINE_line_bottom?
{
while ?LINE = `line`
do
????????echo? " $LINE "
???????? :

done? < ? $FILENAME ?
}
# #####################################
function?while_LINE_line_cmdsub2?
{
cat? $FILENAME ? | ? while ?LINE = $(line)
do
????????echo? " $LINE "
???????? :
done
}
# #####################################
function?while_LINE_line_bottom_cmdsub2?
{
while ?LINE = $(line)
do
????????echo? " $LINE "
???????? :

done? < ? $FILENAME ?
}
# #####################################
function?while_read_LINE_FD?
{
exec ? 3 <& 0
exec ? 0 < ? $FILENAME
while ? read ?LINE
do
????????echo? " $LINE "
???????? :
done
exec ? 0 <& 3
}
# #####################################
function?while_LINE_line_FD?
{
exec ? 3 <& 0
exec ? 0 < ? $FILENAME
while ?LINE = `line`
do
????????echo? " $LINE "
???????? :
done
exec ? 0 <& 3
}
# #####################################
function?while_LINE_line_cmdsub2_FD
{
exec ? 3 <& 0
exec ? 0 < ? $FILENAME
while ?LINE = $(line)
do
???????? print ? " $LINE "
???????? :
done
exec ? 0 <& 3
}
# #####################################
function?while_line_LINE_FD?
{
exec ? 3 <& 0
exec ? 0 < ? $FILENAME

while ?line?LINE
do
????????echo? " $LINE "
???????? :
done

exec ? 0 <& 3
}
# #####################################
###########?START?OF?MAIN?############
######################################

#?Test?the?Input

#?Looking?for?exactly?one?parameter
((?$ # ?==?1?))?||?usage

#?Does?the?file?exist?as?a?regular?file?
[[? - f?$ 1 ?]]? || ?usage

echo? " /nStarting?File?Processing?of?each?Method/n "

echo? " Method?1: "
echo? " /nfunction?while_read_LINE/n " ? >> ? $TIMEFILE
echo? " function?while_read_LINE "
time ?while_read_LINE? >> ? $TIMEFILE
echo? " /nMethod?2: "
echo? " /nfunction?while_read_LINE_bottom/n " ? >> ? $TIMEFILE
echo? " function?while_read_LINE_bottom "
time ?while_read_LINE_bottom? >> ? $TIMEFILE
echo? " /nMethod?3: "
echo? " /nfunction?while_line_LINE_bottom/n " ? >> ? $TIMEFILE
echo? " function?while_line_LINE_bottom "
time ?while_line_LINE_bottom? >> ? $TIMEFILE
echo? " /nMethod?4: "
echo? " /nfunction?cat_while_LINE_line/n " ? >> ? $TIMEFILE
echo? " function?cat_while_LINE_line "
time ?cat_while_LINE_line? >> ? $TIMEFILE
echo? " /nMethod?5: "
echo? " /nfunction?while_line_LINE/n " ? >> ? $TIMEFILE
echo? " function?while_line_LINE "
time ?while_line_LINE? >> ? $TIMEFILE
echo? " /nMethod?6: "
echo? " /nfunction?while_LINE_line_bottom/n " ? >> ? $TIMEFILE
echo? " function?while_LINE_line_bottom "
time ?while_LINE_line_bottom? >> ? $TIMEFILE
echo? " /nMethod?7: "
echo? " /nfunction?while_LINE_line_cmdsub2/n " ? >> ? $TIMEFILE
echo? " function?while_LINE_line_cmdsub2 "
time ?while_LINE_line_cmdsub2? >> ? $TIMEFILE
echo? " /nMethod?8: "
echo? " /nfunction?while_LINE_line_bottom_cmdsub2/n " ? >> ? $TIMEFILE
echo? " function?while_LINE_line_bottom_cmdsub2 "
time ?while_LINE_line_bottom_cmdsub2? >> ? $TIMEFILE
echo? " /nMethod?9: "
echo? " /nfunction?while_read_LINE_FD/n " ? >> ? $TIMEFILE
echo? " function?while_read_LINE_FD "
time ?while_read_LINE_FD? >> ? $TIMEFILE
echo? " /nMethod?10: "
echo? " /nfunction?while_LINE_line_FD/n " ? >> ? $TIMEFILE
echo? " function?while_LINE_line_FD "
time ?while_LINE_line_FD? >> ? $TIMEFILE
echo? " /nMethod?11: "
echo? " /nfunction?while_LINE_line_cmdsub2_FD/n " ? >> ? $TIMEFILE
echo? " function?while_LINE_line_cmdsub2_FD "
time ?while_LINE_line_cmdsub2_FD? >> ? $TIMEFILE
echo? " /nMethod?12: "
echo? " /nfunction?while_line_LINE_FD/n " ? >> ? $TIMEFILE
echo? " function?while_line_LINE_FD "
time ?while_line_LINE_FD? >> ? $TIMEFILE