方法1：使用 shell script 管線導向來實現
程式碼：https://ideone.com/e.js/E0W01z
所需時間：1.085s
方法2：遞迴目錄下的每一檔案並製成HASH索引，讀取檔案清單，依清單比對HASH
程式碼：https://ideone.com/HDhrp6
所需時間：1.298s
由上可知效率上來說：方法1 > 方法4 > 方法2 > 方法3
利用 bash command 和管線(pipe line) 可以快速達到這個結果，如果只是想查看搜尋結果可以這樣：
解答:
#!/usr/bin/awk -f
BEGIN {
}
{
sub(/#.*/,"") # change #.* to ""
for (i=1; i<=NF; i++) {
if ($i ~ /^[0-9]/) { #-----$1 is number
money=$i
if (i==2 || i==3) { #-----money is spends or loses
name=$(i-1)
array[name]=array[name]-money
}
} else { #-----$1 is name
name=$i
money=$(i-1)
array[name]=array[name]+money
}
} #for END
}
END {
for (name in array)
printf("%s has %s\n", name, array[name])
}
執行結果:
解答:
#!/bin/bash
olddir=$PWD
dirdepth=0
function is_last_file {
local flag
let flag=${ary[dirdepth]}-1
if [ $flag -eq 0 ]; then #last file
ch="\\" #as \---
else
ch="|" #as |---
fi
}
function print_file {
is_last_file #check this file is last?
case "$1" in
-D) printf "$ch---$2/\n"
;; #file is directory
-L) printf "$ch---$file --> "
ls -l $file | awk '{ print $11 }'
;; #file is link
-F) printf "$ch---$file\n" #normal file
;; #file is normal file
esac
let ary[dirdepth]=ary[dirdepth]-1
}
function check_file_type {
if [ $dirdepth -gt 0 ]; then
for ((i=0; i<=dirdepth-1; i++)); do
if [ ${ary[i]} -ne 0 ]; then
printf "| " #print | & 3 space
else
printf " " #print 4 space
fi
done # for END
fi
if [ -d "$file" ]; then
print_file -D $file #directory
else
if [ -L $file ]; then
print_file -L $file #symbolic link
else
print_file -F $file #normal file
fi
fi
}
function listfiles {
cd "$1";
f_count=`ls -l | wc -l` #calc total files
let f_count=f_count-1
ary[dirdepth]=$f_count
if [ $f_count -ne 0 ]; then # if dir is empty then exit
for file in *; do
check_file_type $file #call sub
if [ -d "$file" ]; then
let dirdepth=$dirdepth+1
listfiles "$file"
cd ..;
fi
done #for END
fi
let dirdepth=$dirdepth-1
}
#-----Main Program 2017/12/06 update-----
#d=$1
#echo "${d##*/}/"
echo "$(basename "$1")/"
listfiles "$1"
執行結果:
$ ./hanoi 2 # move 2 discs, from A to B by C from A to C from A to B from C to B $ ./hanoi 3 # move 3 discs, from A to B by C from A to B from A to C from B to C from A to B from C to A from C to B from A to B $
解答:
#!/bin/bash
function move_disc {
if [ $1 -ne 0 ]; then
move_disc $(($1-1)) $2 $4 $3
echo from $2 "to" $3
move_disc $(($1-1)) $4 $3 $2
fi
}
#-----Main Program-----
disc=$1
if [ $disc -gt 0 ]; then
move_disc $disc A B C
fi
執行結果:
執行結果:
執行結果:
$ cat ex9-k1
klim 10 20 milk 199 joe 20
# klim is appeared again!
oak 100 red 200 10 klim 30
joe 199 marry 20 julie 2000 #joe joe
$ ./ex9.awk < ex9-k1
klim = 20.00
milk = 199.00
oak = 100.00
red = 105.00
joe = 109.50
marry = 20.00
julie = 2000.00
$
解答:
#!/usr/bin/awk -f
BEGIN {
}
{
sub(/#.*/,"")
if ( $0 != "" ) {
for (i=1; i<=NF; i++) {
if ( $i ~ /[a-z]/ ) { # $1 is name
name=$i
}
else { # $1 is number
array[name]=array[name]+$i
num_count[name]=num_count[name]+1
}
} #for i END
} #if END
}
END {
for (i in array)
printf("%s = %.2f\n",i, array[i]/num_count[i])
}
執行結果:
$ cat k1 10 20 30 #this is a comment 8 7 # this is also a comment 2 $ ./ex8.awk k1 the max three are: 30 20 10 the average is : 12.83 $
解答:
#!/usr/bin/awk -f
BEGIN {
}
{
sub(/#.*/ , "")
if ( $0 != "" ) {
for (i=1; i<=NF; i++) {
num[count]=$i
sum+=$i
count++
} #for END
} #if END
}
END {
asort(num) #sort num[] array
printf("the max three are: %d %d %d\n",num[count],num[count-1],num[count-2])
printf("the average is : %.2f\n",sum/count)
}
注意：程式中asort函數在GNU awk 3.1才有提供
執行結果:
$ cat ex7-k1
klim 10 20 30 milk 199
oak 100 red 200 10
joe 199 20 marry 20 julie 2000
$ ./ex7.sh < ex7-k1
klim = 20.00
milk = 199.00
oak = 100.00
red = 105.00
joe = 109.50
marry = 20.00
julie = 2000.00
$
解答:
#!/bin/bash
function AVERAGE () {
avg=$(echo "scale=2; $2/$3" | bc)
echo "$1 = $avg"
}
function DATA () {
#if [[ $1 != [0-9]* && -n $1 ]]; then
if [[ $1 =~ [a-z]+ && -n $1 ]]; then
#echo "name:$1"
name[index]=$1
let index+=3
sum=0
count=0
else
let sum=sum+$1
if [ ! -z $1 ]; then
let count++
fi
name[index-2]=$sum
name[index-1]=$count
fi
}
index=1
while read line
do
if [ "$line" != "" ]; then
set $(echo $line)
field=$# #*** $# is field count
for ((i=1; i<=field; i++))
do
#echo "data:$1"
DATA $1
shift
done
fi
done #while END
for ((i=1; i<=index-3; i=i+3))
do
#echo "Name:${name[$i]} sum=${name[i+1]} count=${name[i+2]}"
AVERAGE ${name[$i]} ${name[i+1]} ${name[i+2]}
done
執行結果:
解答:
#!/bin/bash
#calc average function
function AVERAGE () {
avg=$(echo "scale=2; $1/$2" | bc )
#echo "the average is : $avg"
}
#bubble sort function
function SORT() {
for ((i=0; i<count; i++))
do
for ((j=i; j<count; j++))
do
if [ ${data[j]} -gt ${data[i]} ]; then
let temp=data[j]
let data[j]=data[i]
let data[i]=temp
fi
done
done
}
if [ -z $1 ]; then #manual input
while read line
do
if [ "$line" != "" ]; then
#set $(echo $line | tr : ' ')
set $(echo $line)
field=$#
for ((i=1; i<=field; i++))
do
data[count]=$1
let sum+=$1
let count+=1
shift
done
else
break
fi
done<&0
else #file(s) input
total_file=$#
for ((i=1; i<=$total_file; i++)) #file name put in f[] array
do
f[i]=$1
shift
done
for ((j=1; j<=$total_file; j++))
do
exec<"${f[j]}"
while read line
do
set $(echo $line)
field=$#
for ((i=1; i<=field; i++))
do
data[count]=$1
let sum+=$1
let count+=1
shift
done
done
done #for END
fi
SORT #Run Bubble sort function
echo "the max three are: ${data[0]} ${data[1]} ${data[2]}"
AVERAGE $sum $count #Run calc average function
echo "the average is : $avg"
執行結果:
解答:
#!/bin/bash
執行結果:
