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Pass arguments into a function - Linux Bash Shell Scripting Tutorial Wiki (cyberciti.biz)

Let us see how to pass parameters to a Bash function.

让我们看看如何向 Bash 函数传递参数。

A shell function is nothing but a set of one or more commands/statements that act as a complete routine.
Each function must have a unique name.
Shell functions have their own command line argument or parameters.
Use shell variable <math xmlns="http://www.w3.org/1998/Math/MathML"> 1 ] ( h t t p s : / / b a s h . c y b e r c i t i . b i z / g u i d e / 1](https://bash.cyberciti.biz/guide/ </math>1](https://bash.cyberciti.biz/guide/1 " <math xmlns="http://www.w3.org/1998/Math/MathML"> 1 " ) , [ 1"), [ </math>1"), [2,..$n to access argument passed to the function.
shell 函数是由一条或多条命令/语句组成的一个完整例程。
每个函数都必须有一个唯一的名称。
shell 函数有自己的命令行参数。
使用 shell 变量 <math xmlns="http://www.w3.org/1998/Math/MathML"> 1 ] ( h t t p s : / / b a s h . c y b e r c i t i . b i z / g u i d e / 1](https://bash.cyberciti.biz/guide/ </math>1](https://bash.cyberciti.biz/guide/1" <math xmlns="http://www.w3.org/1998/Math/MathML"> 1 " ) 、 [ 1")、[ </math>1")、[2...$n 访问传递给函数的参数。

Passing parameters to a Bash function向 Bash 函数传递参数

The syntax is as follows to create user-defined functions in a shell script:

在 shell 脚本中创建用户定义函数的语法如下：

sh 复制代码

function_name(){
   command_block_here
}

## OR ##

function function_name_here(){
   command_line_block
}

## passing parameters to a Bash function ##

my_function_name(){
  arg1=$1
  arg2=$2
  command on $arg1
}

Invoke function

To invoke the the function use the following syntax:

要调用该函数，请使用以下语法：

复制代码

my_function_name foo bar

Where,

my_function_name = Your function name.
foo = Argument # 1 passed to the function (positional parameter # 1).
bar = Argument # 2 passed to the function.
my_function_name = 您的函数名称。
foo = 传递给函数的参数 # 1（位置参数 # 1）。
1. bar = 传递给函数的参数 # 2。

Examples

Create a function called fresh.sh:

创建一个名为 fresh.sh 的函数：

sh 复制代码

#!/bin/bash
 
# write a function
fresh(){
   # t stores $1 argument passed to fresh()
   t=$1
   echo "fresh(): \$0 is $0"
   echo "fresh(): \$1 is $1"
   echo "fresh(): \$t is $t"
   echo "fresh(): total args passed to me $#"
   echo "fresh(): all args (\$@) passed to me -\"$@\""
   echo "fresh(): all args (\$*) passed to me -\"$*\""
}
 
# invoke the function with "Tomato" argument
echo "**** calling fresh() 1st time ****"
fresh Tomato
 
# invoke the function with total 3 arguments
echo "**** calling fresh() 2nd time ****"
fresh Tomato Onion Paneer

Save and close the file. Run it as follows:

保存并关闭文件。按以下步骤运行：

sh 复制代码

chmod +x fresh.sh
./fresh.sh

Sample outputs:

样本输出：

sh 复制代码

**** calling fresh() 1st time ****
fresh(): $0 is ./fresh.sh
fresh(): $1 is Tomato
fresh(): $t is Tomato
fresh(): total args passed to me 1
fresh(): all args ($@) passed to me -"Tomato"
fresh(): all args ($*) passed to me -"Tomato"
**** calling fresh() 2nd time ****
fresh(): $0 is ./fresh.sh
fresh(): $1 is Tomato
fresh(): $t is Tomato
fresh(): total args passed to me 3
fresh(): all args ($@) passed to me -"Tomato Onion Paneer"
fresh(): all args ($*) passed to me -"Tomato Onion Paneer"

Let us try one more example. Create a new shell script to determine if given name is file or directory (cmdargs.sh):

让我们再试一个例子。创建一个新的 shell 脚本来判断给定的名称是文件还是目录（cmdargs.sh）：

sh 复制代码

#!/bin/bash
# Name - cmdargs.sh
# Purpose - Passing positional parameters to user defined function 
# 目的 - 将位置参数传递给用户定义函数 
# -----------------------------------------------------------------
file="$1"

# User-defined function
is_file_dir(){
        # $f is local variable
	local f="$1"
        # file attributes comparisons using test i.e. [ ... ]
	[ -f "$f" ] && { echo "$f is a regular file."; exit 0; }
	[ -d "$f" ] && { echo "$f is a directory."; exit 0; }
	[ -L "$f" ] && { echo "$f is a symbolic link."; exit 0; }
	[ -x "$f" ] && { echo "$f is an executeble file."; exit 0; }
}

# make sure filename supplied as command line arg else die
# 确保文件名作为命令行参数提供，否则 die
[ $# -eq 0 ] && { echo "Usage: $0 filename"; exit 1; }

# invoke the is_file_dir and pass $file as arg
# 调用 is_file_dir，并将 $file 作为参数传入
is_file_dir "$file

Run it as follows:

运行方法如下

sh 复制代码

./cmdargs.sh /etc/resolv.conf
./cmdargs.sh /bin/date
./cmdargs.sh $HOME
./cmdargs.sh /sbin

Sample outputs:

样本输出：

sh 复制代码

/etc/resolv.conf is a regular file.
/bin/date is a regular file.
/home/vivek is a directory.
/sbin is a directory.

Function shell variables

All function parameters or arguments can be accessed via <math xmlns="http://www.w3.org/1998/Math/MathML"> 1 , 1, </math>1,2, <math xmlns="http://www.w3.org/1998/Math/MathML"> 3 , . . . , 3,..., </math>3,...,N.
$0 \] ( h t t p s : / / b a s h . c y b e r c i t i . b i z / g u i d e / 0\](https://bash.cyberciti.biz/guide/$
$#\](https://bash.cyberciti.biz/guide/ "$") holds the number of positional parameters passed to the function.$
$0 \] ( h t t p s : / / b a s h . c y b e r c i t i . b i z / g u i d e / 0\](https://bash.cyberciti.biz/guide/$
$#\](https://bash.cyberciti.biz/guide/ "$") 保存传递给函数的位置参数的个数。$

0 \] ( h t t p s : / / b a s h . c y b e r c i t i . b i z / g u i d e / 0\](https://bash.cyberciti.biz/guide/

【Linux】Pass arguments into a function

Source

Passing parameters to a Bash function向 Bash 函数传递参数

Invoke function

Examples

Function shell variables