在 Bash 中循环遍历字符串数组？

Question

提问by Mo.

I want to write a script that loops through 15 strings (array possibly?) Is that possible?

我想编写一个循环遍历 15 个字符串（可能是数组？）的脚本，这可能吗？

Something like:

就像是：

for databaseName in listOfNames
then
  # Do something
end

Answer 1

回答by anubhava

You can use it like this:

你可以这样使用它：

## declare an array variable
declare -a arr=("element1" "element2" "element3")

## now loop through the above array
for i in "${arr[@]}"
do
   echo "$i"
   # or do whatever with individual element of the array
done

# You can access them using echo "${arr[0]}", "${arr[1]}" also

Also works for multi-line array declaration

也适用于多行数组声明

declare -a arr=("element1" 
                "element2" "element3"
                "element4"
                )

Answer 2

回答by 4ndrew

That is possible, of course.

当然，这是可能的。

for databaseName in a b c d e f; do
  # do something like: echo $databaseName
done

See Bash Loops for, while and untilfor details.

有关详细信息，请参阅Bash 循环 for、while 和 until。

Answer 3

回答by caktux

None of those answers include a counter...

这些答案都不包括计数器......

#!/bin/bash
## declare an array variable
declare -a array=("one" "two" "three")

# get length of an array
arraylength=${#array[@]}

# use for loop to read all values and indexes
for (( i=1; i<${arraylength}+1; i++ ));
do
  echo $i " / " ${arraylength} " : " ${array[$i-1]}
done

Output:

输出：

1  /  3  :  one
2  /  3  :  two
3  /  3  :  three

Answer 4

回答by FireInTheSky

Yes

是的

for Item in Item1 Item2 Item3 Item4 ;
  do
    echo $Item
  done

Output:

输出：

Item1
Item2
Item3
Item4

To preserve spaces; single or double quote list entries and double quote list expansions.

保留空间；单引号或双引号列表条目和双引号列表扩展。

for Item in 'Item 1' 'Item 2' 'Item 3' 'Item 4' ;
  do
    echo "$Item"
  done

Output:

输出：

Item 1
Item 2
Item 3
Item 4

To make list over multiple lines

制作多行列表

for Item in Item1 \
            Item2 \
            Item3 \
            Item4
  do
    echo $Item
  done

Output:

输出：

Item1
Item2
Item3
Item4

Simple list variable

简单列表变量

List=( Item1 Item2 Item3 )

or

或者

List=(
      Item1 
      Item2 
      Item3
     )

Display the list variable:

显示列表变量：

echo ${List[*]}

Output:

输出：

Item1 Item2 Item3

Loop through the list:

循环遍历列表：

for Item in ${List[*]} 
  do
    echo $Item 
  done

Output:

输出：

Item1
Item2
Item3

Create a function to go through a list:

创建一个函数来遍历列表：

Loop(){
  for item in ${*} ; 
    do 
      echo ${item} 
    done
}
Loop ${List[*]}

Using the declare keyword (command) to create the list, which is technically called an array:

使用declare关键字（命令）创建列表，技术上称为数组：

declare -a List=(
                 "element 1" 
                 "element 2" 
                 "element 3"
                )
for entry in "${List[@]}"
   do
     echo "$entry"
   done

Output:

输出：

element 1
element 2
element 3

Creating an associative array. A dictionary:

创建关联数组。一本字典：

declare -A continent

continent[Vietnam]=Asia
continent[France]=Europe
continent[Argentina]=America

for item in "${!continent[@]}"; 
  do
    printf "$item is in ${continent[$item]} \n"
  done

Output:

输出：

 Argentina is in America
 Vietnam is in Asia
 France is in Europe

CVS variables or files in to a list.
Changing the internal field separator from a space, to what ever you want.
In the example below it is changed to a comma

将 CVS 变量或文件放入一个列表中。
将内部字段分隔符从空格更改为您想要的任何内容。
在下面的示例中，它更改为逗号

List="Item 1,Item 2,Item 3"
Backup_of_internal_field_separator=$IFS
IFS=,
for item in $List; 
  do
    echo $item
  done
IFS=$Backup_of_internal_field_separator

Output:

输出：

Item 1
Item 2
Item 3

If need to number them:

如果需要给它们编号：

this is called a back tick. Put the command inside back ticks.

这称为回勾。将命令放在后面的刻度内。

`commend`

It is next to the number one on your keyboard and or above the tab key. On a standard american english language keyboard.

它位于键盘上的数字旁边或 Tab 键上方。在标准的美式英语键盘上。

List=()
Start_count=0
Step_count=0.1
Stop_count=1
for Item in `seq $Start_count $Step_count $Stop_count`
    do 
       List+=(Item_$Item)
    done
for Item in ${List[*]}
    do 
        echo $Item
    done

Output is:

输出是：

Item_0.0
Item_0.1
Item_0.2
Item_0.3
Item_0.4
Item_0.5
Item_0.6
Item_0.7
Item_0.8
Item_0.9
Item_1.0

Becoming more familiar with bashes behavior:

更加熟悉 bashes 行为：

Create a list in a file

在文件中创建列表

cat <<EOF> List_entries.txt
Item1
Item 2 
'Item 3'
"Item 4"
Item 7 : *
"Item 6 : * "
"Item 6 : *"
Item 8 : $PWD
'Item 8 : $PWD'
"Item 9 : $PWD"
EOF

Read the list file in to a list and display

将列表文件读入列表并显示

List=$(cat List_entries.txt)
echo $List
echo '$List'
echo "$List"
echo ${List[*]}
echo '${List[*]}'
echo "${List[*]}"
echo ${List[@]}
echo '${List[@]}'
echo "${List[@]}"

BASH commandline reference manual: Special meaning of certain characters or words to the shell.

BASH 命令行参考手册：某些字符或单词对 shell 的特殊含义。

Answer 5

回答by user2533809

In the same spirit as 4ndrew's answer:

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. No whitespace in the names:

B. 名称中没有空格：

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

Notes

笔记

In the second example, using listOfNames="RA RB R C RD"has the same output.

在第二个示例中， usinglistOfNames="RA RB R C RD"具有相同的输出。

Other ways to bring in data include:

其他引入数据的方法包括：

stdin (listed below),
variables,
an array(the accepted answer),
a file...

标准输入（如下所列），
变量,
一个数组（接受的答案），
一个文件...

Read from stdin

从标准输入读取

# 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

the bash IFS"field separator to line" [1] delimiter can be specified in the script to allow other whitespace (i.e. IFS='\n', or for MacOS IFS='\r')
I like the accepted answer also :) -- I've include these snippets as other helpful ways that also answer the question.
Including #!/bin/bashat the top of the script file indicates the execution environment.
It took me months to figure out how to code this simply :)

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'，或用于 MacOS IFS='\r'）
我也喜欢接受的答案 :) -- 我已经将这些片段作为其他有用的方法也可以回答这个问题。
包含#!/bin/bash在脚本文件顶部的表示执行环境。
我花了几个月的时间才弄清楚如何简单地编写代码:)

Other Sources (while read loop)

其他来源（while read loop）

Answer 6

回答by Fizer Khan

You can use the syntax of ${arrayName[@]}

您可以使用以下语法 ${arrayName[@]}

#!/bin/bash
# declare an array called files, that contains 3 values
files=( "/etc/passwd" "/etc/group" "/etc/hosts" )
for i in "${files[@]}"
do
    echo "$i"
done

Answer 7

回答by Doorknob

Surprised that nobody's posted this yet -- if you need the indices of the elements while you're looping through the array, you can do this:

令人惊讶的是还没有人发布这个 - 如果您在遍历数组时需要元素的索引，您可以这样做：

arr=(foo bar baz)

for i in ${!arr[@]}
do
    echo $i "${arr[i]}"
done

Output:

输出：

0 foo
1 bar
2 baz

I find this a lot more elegant than the "traditional" for-loop style (for (( i=0; i<${#arr[@]}; i++ ))).

我发现这比“传统” for 循环样式 ( for (( i=0; i<${#arr[@]}; i++ )))优雅得多。

(${!arr[@]}and $idon't need to be quoted because they're just numbers; some would suggest quoting them anyway, but that's just personal preference.)

（${!arr[@]}并且$i不需要引用，因为它们只是数字；有些人会建议无论如何引用它们，但这只是个人喜好。）

Answer 8

回答by Treethawat Thanawachiramate

This is also easy to read:

这也很容易阅读：

FilePath=(
    "/tmp/path1/"    #FilePath[0]
    "/tmp/path2/"    #FilePath[1]
)

#Loop
for Path in "${FilePath[@]}"
do
    echo "$Path"
done

Answer 9

回答by F. Hauri

Implicit array for script or functions:

脚本或函数的隐式数组：

In addition to anubhava's correct answer: If basic syntax for loop is:

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

there is a specialcase in bash:

bash 中有一个特殊情况：

When running a script or a function, argumentspassed at command lines will be assigned to $@array variable, you can access by $1, $2, $3, and so on.

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

This can be populated (for test) by

这可以填充（用于测试）

set -- arg1 arg2 arg3 ...

A loopover thisarray could be written simply:

一个循环在这个阵列可以简单地写成：

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

Notethat the reserved work inis not present and no array name too!

请注意，保留的工作in不存在，也没有数组名称！

Sample:

样本：

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: ....

Note that this is same than

请注意，这与

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

Then into a script:

然后进入一个脚本：

#!/bin/bash

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

Save this in a script myscript.sh, chmod +x myscript.sh, then

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

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

Same in a function:

在函数中相同：

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

Then

然后

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

Answer 10

回答by rashedcs

Simple way :

简单的方法：

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}

在 Bash 中循环遍历字符串数组？

提问by Mo.

回答by anubhava

回答by 4ndrew

回答by caktux

回答by FireInTheSky

回答by user2533809

回答by Fizer Khan

回答by Doorknob

回答by Treethawat Thanawachiramate

回答by F. Hauri

Implicit array for script or functions:

脚本或函数的隐式数组：

Then into a script:

然后进入一个脚本：

Same in a function:

在函数中相同：

回答by rashedcs

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在 Bash 中循环遍历字符串数组？

提问by Mo.

回答by anubhava

回答by 4ndrew

回答by caktux

回答by FireInTheSky

回答by user2533809

回答by Fizer Khan

回答by Doorknob

回答by Treethawat Thanawachiramate

回答by F. Hauri

Implicit array for script or functions:

脚本或函数的隐式数组：

Then into a script:

然后进入一个脚本：

Same in a function:

在函数中相同：

回答by rashedcs

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