我想写一个循环15个字符串的脚本(可能是数组?)这可能吗?

类似于:

for databaseName in listOfNames
then
  # Do something
end

当前回答

循环遍历数组的方式取决于换行符的存在。使用分隔数组元素的换行符,数组可以称为“$array”,否则应称为“${array[@]}”。以下脚本将明确说明:

#!/bin/bash

mkdir temp
mkdir temp/aaa
mkdir temp/bbb
mkdir temp/ccc
array=$(ls temp)
array1=(aaa bbb ccc)
array2=$(echo -e "aaa\nbbb\nccc")

echo '$array'
echo "$array"
echo
for dirname in "$array"; do
    echo "$dirname"
done
echo
for dirname in "${array[@]}"; do
    echo "$dirname"
done
echo
echo '$array1'
echo "$array1"
echo
for dirname in "$array1"; do
    echo "$dirname"
done
echo
for dirname in "${array1[@]}"; do
    echo "$dirname"
done
echo
echo '$array2'
echo "$array2"
echo
for dirname in "$array2"; do
    echo "$dirname"
done
echo
for dirname in "${array2[@]}"; do
    echo "$dirname"
done
rmdir temp/aaa
rmdir temp/bbb
rmdir temp/ccc
rmdir temp

其他回答

本着与4ndrew的回答相同的精神:

listOfNames="RA
RB
R C
RD"

# To allow for other whitespace in the string:
# 1. add double quotes around the list variable, or
# 2. see the IFS note (under 'Side Notes')

for databaseName in "$listOfNames"   #  <-- Note: Added "" quotes.
do
  echo "$databaseName"  # (i.e. do action / processing of $databaseName here...)
done

# Outputs
# RA
# RB
# R C
# RD

B.名称中无空格:

listOfNames="RA
RB
R C
RD"

for databaseName in $listOfNames  # Note: No quotes
do
  echo "$databaseName"  # (i.e. do action / processing of $databaseName here...)
done

# Outputs
# RA
# RB
# R
# C
# RD

笔记

在第二个示例中,使用listOfNames=“RA RB R C RD”具有相同的输出。

其他引入数据的方法包括:

stdin(如下所列),变量,数组(接受的答案),文件。。。

从stdin读取

# line delimited (each databaseName is stored on a line)
while read databaseName
do
  echo "$databaseName"  # i.e. do action / processing of $databaseName here...
done # <<< or_another_input_method_here

可以在脚本中指定bash IFS“字段分隔符到行”[1]分隔符,以允许其他空格(即IFS='\n',或MacOS IFS='\r')我也喜欢接受的答案:)--我将这些片段作为其他有用的方式来回答这个问题。包括#/脚本文件顶部的bin/bash指示执行环境。我花了几个月的时间才弄清楚如何简单地编写代码:)

其他来源(读取循环时)

listOfNames="db_one db_two db_three"
for databaseName in $listOfNames
do
  echo $databaseName
done

或者只是

for databaseName in db_one db_two db_three
do
  echo $databaseName
done

试试这个。它正在运行和测试。

for k in "${array[@]}"
do
    echo $k
done

# For accessing with the echo command: echo ${array[0]}, ${array[1]}

简单方法:

arr=("sharlock"  "bomkesh"  "feluda" )  ##declare array

len=${#arr[*]}  # it returns the array length

#iterate with while loop
i=0
while [ $i -lt $len ]
do
    echo ${arr[$i]}
    i=$((i+1))
done


#iterate with for loop
for i in $arr
do
  echo $i
done

#iterate with splice
 echo ${arr[@]:0:3}

脚本或函数的隐式数组:

除了anubhava的正确答案:如果循环的基本语法是:

for var in "${arr[@]}" ;do ...$var... ;done

bash中有一个特殊情况:

当运行脚本或函数时,在命令行传递的参数将被分配给$@数组变量,您可以通过$1、$2、$3等进行访问。

可以通过以下方式填充(用于测试)

set -- arg1 arg2 arg3 ...

这个数组上的循环可以简单地写:

for item ;do
    echo "This is item: $item."
  done

请注意,中的保留工作不存在,也没有数组名称!

示例:

set -- arg1 arg2 arg3 ...
for item ;do
    echo "This is item: $item."
  done
This is item: arg1.
This is item: arg2.
This is item: arg3.
This is item: ....

注意,这与

for item in "$@";do
    echo "This is item: $item."
  done

然后进入脚本:

#!/bin/bash

for item ;do
    printf "Doing something with '%s'.\n" "$item"
  done

将其保存在脚本myscript.sh、chmod+x myscript.shh中,然后

./myscript.sh arg1 arg2 arg3 ...
Doing something with 'arg1'.
Doing something with 'arg2'.
Doing something with 'arg3'.
Doing something with '...'.

在函数中相同:

myfunc() { for item;do cat <<<"Working about '$item'."; done ; }

Then

myfunc item1 tiem2 time3
Working about 'item1'.
Working about 'tiem2'.
Working about 'time3'.