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比较从文件中读取的两个数字

tag-icon • tag-icon bash shell-script
比较从文件中读取的两个数字

我有一个脚本可以读取标准格式的文件，其中第 9 个单词是数字。我正在尝试比较从文件中读取的数字。我能够正确地读取该行，并且它完全按照我想要的方式工作。但我收到一条错误消息：

./age.sh: line 8: [: age: integer expression expected

这是我的脚本：

#!/bin/bash
if [ -f $1 ] ;
then
    while read -r LINE || [[ -n $LINE ]]; do
        name=$( echo $LINE | cut -d " " -f1 -f2)
        ago=$( echo $LINE | cut -d " " -f9)     
        echo "$name ----- $age"
        if [ $ago -gt 30 ] ; then
            echo "You get a discount"
        fi
    done < $1
    else
        echo "No file found"
fi

这是一个示例输入文件

#FirstName LastName SuperheroName Powers Weapons City Enemy isOutOfEarth Age
Bruce Wayne Batman Martial_arts No_Guns Gowtham Joker No 31
Clark Kent Superman Extreme_strength None Metropolitan Lex_Luther Yes 32
Oliver Queen Green_arrow Accuracy Bow_and_Arrow Star_city Cupid No 30

答案1

您收到的具体错误是因为您的脚本也在处理文件的标头。一个简单的解决方法是跳过以 开头的行#：

#!/bin/bash
if [ ! -f "$1" ]; then
   echo "No file found"
   exit 1
fi

## Use grep -v to print lines that don't match the pattern given. 
grep -v '^#' "$1" | 
while read -r LINE || [ -n "$LINE" ]; do
   name=$( echo "$LINE" | cut -d " " -f1,2)
   age=$( echo "$LINE" | cut -d " " -f9)
   echo "$name ----- $age"
   if [ "$age" -gt 30 ]; then
      echo "You got a discount"
   fi
done

但是，由于您可能还想对其他列进行操作，因此我将直接将它们全部读入变量中：

#!/bin/bash
if [ ! -f "$1" ]; then
   echo "No file found"
   exit 1
fi

## read can take multiple values and splits the input line on whitespace
## automatically. Each field is assigned to one of the variables given.
## If there are more fields than variable names, the remaining fields
## are all assigned to the last variable.
grep -v '^#' "$1" | while read -r first last super powers weapons city enemy isout age; do
   echo "$first $last  ----- $age"
   if [ "$age" -gt 30 ]; then
      echo "You got a discount"
   fi
done

答案2

#!/bin/bash 
if [ ! -f "$1" ]; then
   echo "No file found"
   exit 1
fi

exec < $1

while read -r LINE || [ -n "$LINE" ]; do
   name=$( echo "$LINE" | cut -d " " -f1,2)
   age=$( echo "$LINE" | cut -d " " -f9)
   echo "$name ----- $age"
   if [ "$age" -gt 30 ]; then
      echo "You got a discount"
   fi
done

答案3

这就是我所做的：

#!/bin/bash

if [ -f $1 ] ; 
then 
    sum=0
    echo "#FirstName LastName City Age" 
    while read -r LINE || [[ -n $LINE ]]; do 
       name=$( echo $LINE | cut -d " " -f1 -f2) 
       city=$( echo $LINE | cut -d " " -f3) 
       age=$( echo $LINE | cut -d " " -f9) 
       check=$( echo $amount | grep -c "[0-9]") 
       if [ $check -gt 0 ]; then 
         if [ $age -gt 30 ] ; then 
            echo "You get a discount" 
         fi 
       fi 
    done < $1 

else 
    echo "No file found" 
fi

答案4

我将该行读入 bash 数组：

if [[ -f $1 ]] ; then
    while read -ra line; do
        (( ${#line[@]} > 0 )) || continue  # skip empty lines
        name=${line[*]:0:2}
        age=${line[-1]}
        echo "$name ----- $age"
        if (( $age > 30 )); then
            echo "You get a discount"
        fi
    done < "$1"
else
    echo "No file found"
fi

#FirstName LastName ----- Age
Bruce Wayne ----- 31
You get a discount
Clark Kent ----- 32
You get a discount
Oliver Queen ----- 30

这也不会因为 $age 是非整数而受到困扰：

$ age=Age
$ [ $age -gt 30 ] && echo old || echo young
bash: [: Age: integer expression expected
young
$ (( $age > 30 )) && echo old || echo young
young
$ [[ $age -gt 30 ]] && echo old || echo young
young

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