linux shell之字元串的更具字元分割和删除字元和文本内容的删除以及内容是否比對成功

1  字元串的更具字元分割

1） xargs分割

echo "chenyu*hello*word" | xargs -d "*"
chenyu hello word      

2） awk分割

echo "chenyu*hello*word" | awk -F "*" '{print $1}'
chenyu      

2 字元串的删除字元

1）用tr指令

1. echo "chenyu ni hao ya" | tr -d 'y'
2. chenu ni hao a      

2）用sed指令

1. echo  "hello*word*word" | sed 's/*//g'
2. hellowordword      

3 文本内容的删除

用sed指令

cat 1.txt
chenyu
nihao
hello
word
chenyu
nihao
dongma
sed -i '/chenyu/d' 1.txt
cat 1.txt
nihao
hello
word
nihao
dongma      

4 grep -q 用于if邏輯判斷

-q 參數，本意是 Quiet; do not write anything to standard output. Exit immediately with zero status if any match is found, even if an error was detected.  中文意思為，安靜模式，不列印任何标準輸出。如果有比對的内容則立即傳回狀态值0

自己測試如下

#/bin/bash
 
value="chenyu ni hao ya"
 
#比對成功執行$?傳回0
echo "hello" | grep -q "he";
echo $?
#比對失敗執行$?非0
echo "hello" | grep -q "hehelodaf";
echo $?
 
#如果能比對成功那麼就到then反之到else
if echo $value | grep -q "chenyuddsa"; 
then
   echo "first success" 
else
   echo "first fail"
fi
 
 
if echo $value | grep -q "hao"; 
then
   echo "second success" 
else
   echo "second fail"
fi      

允許結果如下：

1. ./grep.sh
2. 0
3. 1
4. first fail
5. second success      

5 grep -i（忽略大小寫）來判斷結果

#/bin/bash
 
value="chenyu"
echo $value | grep -i "chen" > /dev/null
 
if [ $? -eq 0 ];
then
    echo "grep success"
else
    echo "grep fail"
fi
 
echo $value | grep -i "chengongyu" > /dev/null
 
if [ $? -eq 0 ];
then
    echo "grep success"
else
    echo "grep fail"
fi
 
 
 
       

運作結果

1. grep success
2. grep fail