bash - 用 bash 脚本编写文件

Question

我是 bash 的新手，但我正在尝试编写一个执行以下操作的 bash 脚本：

write_to_file()
{
 #check if file exists
 # if not create the file
 # else open the file to edit
 # go in a while loop
 # ask input from user 
 # write to the end of the file
 # until user types  ":q"

 }

如果有人能指出文献，我将非常感谢谢谢

Answer 1

更新：因为这是一个 bash 问题，你应该先试试这个。;)

cat <<':q' >> test.file

要了解发生了什么，请阅读 bash 的IO 重定向、heredoc 语法和cat命令

---

正如您在上面看到的，有很多方法可以做到这一点。为了解释更多 bash 命令，我还按照您的要求准备了该函数：

#!/bin/bash

write_to_file()
{

     # initialize a local var
     local file="test.file"

     # check if file exists. this is not required as echo >> would 
     # would create it any way. but for this example I've added it for you
     # -f checks if a file exists. The ! operator negates the result
     if [ ! -f "$file" ] ; then
         # if not create the file
         touch "$file"
     fi

     # "open the file to edit" ... not required. echo will do

     # go in a while loop
     while true ; do
        # ask input from user. read will store the 
        # line buffered user input in the var $user_input
        # line buffered means that read returns if the user
        # presses return
        read user_input

        # until user types  ":q" ... using the == operator
        if [ "$user_input" = ":q" ] ; then
            return # return from function
        fi

        # write to the end of the file. if the file 
        # not already exists it will be created
        echo "$user_input" >> "$file"
     done
 }

# execute it
write_to_file

Answer 2

带有基本参数检查的示例：

write_to_file()
{
    while [ "$line" != ":q" ]; do
        read line
        if [ "$line" != ":q" ]; then
            printf "%s\n" "$line" >> "$1"
        fi  
    done
}

if [ "$#" -eq 1 ]; then
    write_to_file "$1"
else
    echo "Usage: $0 FILENAME"
    exit 2
fi

---

或者使用可能鲜为人知的until构造，该函数可以写得更简洁：

# append to file ($1) user supplied lines until `:q` is entered
write_to_file()
{
    until read line && [ "$line" = ":q" ]; do
        printf "%s\n" "$line" >> "$1"
    done
}

Answer 3

这个快速示例应该可以帮助您入门：

while true
do
    read INPUT
    if [[ "${INPUT}" == :q ]]
    then
        return
    fi
    echo "${INPUT}" >> file
done

Answer 4

这里有几个解决方案太难了。做就是了：

write_to_file() { sed '/^:q$/q' | sed '$d' >>"$1"; }

其中第一个参数是文件名。也就是说，将其调用为：

write_to_file test.file