Linux&shell之结构化命令进阶

#!/bin/bash
# basic for command
for test in A B C D E F G H I J K L M N O P Q
do
  echo The next letter is $test
done

#!/bin/bash
# basic for command
for test in A B C D
do
  echo The next letter is $test
done
echo "The last letter is $test"
test=Z
echo "Wait,now the letter is $test"

#!/bin/bash
# basic for command
for test in I don't know if this'll work
do
  echo "word:$test"
done

#!/bin/bash
# basic for command
for test in I don\'t know if this\'ll work
do
  echo "word:$test"
done
或
#!/bin/bash
# basic for command
for test in I "don't" know if "this'll" work  
do
  echo "word:$test"
done

#!/bin/bash
# basic for command
for test in Nevada New Hampshire New Mexico New York North Carolina
do
  echo "Now going to $test"
done

#!/bin/bash
# basic for command
for test in Nevada "New Hampshire" "New Mexico" "New York" "North Carolina"
do
  echo "Now going to $test"
done

#!/bin/bash
# using a variable to hold the list
list="Beijing Shanghai Guangzhou Shenzhen Nanjing Hangzhou"
list=$list" Suzhou"

for city in $list
do
  echo "Have you ever visited $city"
done

#!/bin/bash
# reading values from a file
file="cities"

for city in `cat $file`
do
  echo "Have you ever visited $city"
done

#!/bin/bash
# reading values from a file
file="cities"

IFS=$'\n'
for city in `cat $file`
do
  echo "Have you ever visited $city"
done

#!/bin/bash
#iterate through all the files in a directory

for file in /home/* /home/jiqing9006/shellscript/*
do
  if [ -d "$file" ]
  then
    echo "$file is a directory"
  elif [ -f "$file" ]
  then
    echo "$file is a file"
  fi
done

#!/bin/bash
#testing the C-style for loop
for((i=1;i<=10;i++))
do
  echo "The next number is $i"
done

#!/bin/bash
#testing the C-style for loop
for((a=1,b=10;a<=10;a++,b--))
do
  echo "$a-$b"
done

#!/bin/bash
#testing the C-style for loop
for((a=1,b=10;a<=10;a++,b--))
do
  echo $[ $a-$b ]
done

#!/bin/bash
# while command test
var1=10
while [ $var1 -gt 0 ]
do
  echo $var1
  var1=$[ $var1 - 1 ]
done

#!/bin/bash
# while command test
var1=10
while echo $var1
      [ $var1 -gt 0 ]
do
  echo "This is inside the loop"
  var1=$[ $var1 - 1 ]
done

#!/bin/bash
# using the until command
var1=100
until [ $var1 -gt 0 ]
do
  echo $var1
  var1=$[ $var1 -25 ]
done

#!/bin/bash
# nesting for loops
for((a = 1;a<=3;a++))
do
  echo "Starting loop $a:"
  for((b=1;b<=3;b++))
  do
    echo "Inside loop:$b"
  done
done

#!/bin/bash
# placing a for loop inside a while loop
var1=5
while [ $var1 -ge 0 ]
do
  echo "Outer loop:$var1"
  for((var2=1;var2<3;var2++))
  do
    var3=$[ $var1*$var2 ]
    echo "Inner loop:$var1*$var2 = $var3"
  done
  var1=$[$var1 -1]
done

#!/bin/bash
#using until and while loops
var1=3
until [ $var1 -eq 0 ]
do
  echo "Outer loop:$var1"
  var2=1
  while [ $var2 -lt 5 ]
  do
    var3=`echo "scale=4;$var1/$var2"|bc`
    echo "  Inner loop:$var1/$var2 = $var3"
    var2=$[ $var2 +1 ]
  done
  var1=$[ $var1 - 1 ]
done

#!/bin/bash
# breaking out of a for loop

for var1 in 1 2 3 4 5 6 7 8 9 10
do
  if [ $var1 -eq 5 ]
  then
    break
  fi
  echo "number:$var1"
done
echo "The for loop is completed"

#!/bin/bash
# breaking out of a while loop

var1=1

while [ $var1 -lt 10 ]
do
  if [ $var1 -eq 5 ]
  then
    break
  fi
  echo "number:$var1"
  var1=$[ $var1 + 1 ]
done
echo "The while loop is completed"

#!/bin/bash
# breaking out of an inner loop

for ((a=1;a<4;a++))
do
  echo "Outer loop:$a"
  for((b=1;b<100;b++))
  do
    if [ $b -eq 5 ]
    then
      break
    fi
    echo "  Inner loop:$b"
  done
done

#!/bin/bash
# breaking out of an inner loop

for ((a=1;a<4;a++))
do
  echo "Outer loop:$a"
  for((b=1;b<100;b++))
  do
    if [ $b -eq 5 ]
    then
      break 2
    fi
    echo "  Inner loop:$b"
  done
done

#!/bin/bash
# using the continue command

for((var1 = 1;var1<15;var1++))
do
  if [ $var1 -gt 5 ]&&[ $var1 -lt 10 ]
  then
    continue
  fi
  echo "Iteration number:$var1"
done

#!/bin/bash
# using the continue command

for((a=1;a<=5;a++))
do
  echo "Iteration $a:"
  for((b=1;b<=10;b++))
  do
    if [ $a -gt 3 ]&&[ $b -lt 5 ]
    then
      continue
    fi
    res=$[ $a*$b ]
    echo "The result of $a*$b is:$res"
  done
done

#!/bin/bash
# using the continue command

for((a=1;a<=5;a++))
do
  echo "Iteration $a:"
  for((b=1;b<=10;b++))
  do
    if [ $a -gt 3 ]&&[ $b -lt 5 ]
    then
      continue 2
    fi
    res=$[ $a*$b ]
    echo "The result of $a*$b is:$res"
  done
done

#!/bin/bash
# using the continue command

for((a=1;a<=5;a++))
do
  echo "Iteration $a:"
  for((b=1;b<=10;b++))
  do
    if [ $a -gt 3 ]&&[ $b -lt 5 ]
    then
      break
    fi
    res=$[ $a*$b ]
    echo "The result of $a*$b is:$res"
  done
done

#!/bin/bash
# using the continue command

for((a=1;a<=5;a++))
do
  echo "Iteration $a:"
  for((b=1;b<=10;b++))
  do
    if [ $a -gt 3 ]&&[ $b -lt 5 ]
    then
      break 2
    fi
    res=$[ $a*$b ]
    echo "The result of $a*$b is:$res"
  done
done

#!/bin/bash
# using the continue command

for((a=1;a<=5;a++))
do
  echo "Iteration $a:"
  for((b=1;b<=10;b++))
  do
    if [ $a -gt 3 ]&&[ $b -lt 5 ]
    then
      break
    fi
    res=$[ $a*$b ]
    echo "The result of $a*$b is:$res"
  done
done > output.txt