無法在 shell 腳本中正確地從 IP 地址中提取八位字節

ipfile.txt格式如下：

ServerA 127.0.0.1
ServerB 192.168.1.254
ServerC 4.2.2.1

shell腳本的期望輸出：

ServerA   Class A
ServerB   Class C
ServerC   Class A

我想不出更好的方法來只提取第一個八位字節。到目前為止，我的腳本是：

#!/bin/bash

# Take input IP from file and classify according to classful addressing. 

while read ip;do
       octet=$(awk -F'[ .]' '{print $2}' ipfile.txt)
       if [[ "$octet" -ge 1 && "$octet" -le 127 ]];then
               echo "ServerA Class A"
       fi
       if [[ "$octet" -ge 128 && "$octet" -le 191 ]];then
               echo "ServerB Class B"
       fi
       if [[ "$octet" -ge 192 && "$octet" -le 223 ]];then
               echo "ServerC Class C"
       fi
done < ipfile.txt

我收到語法錯誤：

./ipclassgen.sh: line 7: [[: 127
192
4: syntax error in expression (error token is "192
4")
./ipclassgen.sh: line 10: [[: 127
192
4: syntax error in expression (error token is "192
4")
./ipclassgen.sh: line 13: [[: 127
192
4: syntax error in expression (error token is "192
4")
./ipclassgen.sh: line 7: [[: 127
192
4: syntax error in expression (error token is "192
4")
./ipclassgen.sh: line 10: [[: 127
192
4: syntax error in expression (error token is "192
4")
./ipclassgen.sh: line 13: [[: 127
192
4: syntax error in expression (error token is "192
4")
./ipclassgen.sh: line 7: [[: 127
192
4: syntax error in expression (error token is "192
4")
./ipclassgen.sh: line 10: [[: 127
192
4: syntax error in expression (error token is "192
4")
./ipclassgen.sh: line 13: [[: 127
192
4: syntax error in expression (error token is "192
4")
./ipclassgen.sh: line 7: [[: 127
192
4: syntax error in expression (error token is "192
4")
./ipclassgen.sh: line 10: [[: 127
192
4: syntax error in expression (error token is "192
4")
./ipclassgen.sh: line 13: [[: 127
192
4: syntax error in expression (error token is "192
4")

如何在不使用 awk 和指定文件的情況下做到這一點。我也不確定語法錯誤在哪裡。

您將文件逐行讀取到ip變數中，但從不使用它。然後將所有行的第二個欄位分配給octet變數，由<NL>(\n, 0x0A) 分隔，再次讀取文件。然後在進行測試時bash偶然發現了多行。octet請嘗試：

while read server ip
 do    octet=${ip%%.*}
.
.
.
 done < file

另請注意，不硬編碼伺服器名稱而是使用server從文件中讀取的變數可能更聰明：

if [[ "$octet" -ge 1 && "$octet" -le 127 ]]
 then  echo "$server: Class A"
 fi

PS：您甚至可以read為您拆分線路：

while IFS=" ." read server ip1 ip2 ip3 ip4
 do if [[ "$ip1" ...

引用自：https://unix.stackexchange.com/questions/700536