shell - shell 脚本中预期的条件二元运算符

Question

我正在尝试一个简单的程序来比较存储在日志文件中的字符串值，但出现如下错误，

#!/bin/bash

check_val1="successful"
check_val2="completed"
log="/compile.log"

if [[ grep $check_val1 $log -ne $check_val1 || grep $check_val2 $log -ne $check_val2 ]];
then
        echo "No Error"
else
        echo "Error"
fi


Error:

./simple.sh: line 7: conditional binary operator expected
./simple.sh: line 7: syntax error near `$check_val1'
./simple.sh: line 7: `if [[ grep $check_val1 $log -ne $check_val1 || grep $check_val2 $log -ne $check_val2 ]];'

Answer 1

问题出在您的 if [[...]]您使用的表达式 2 grep不使用命令替换的命令，即 $(grep 'pattern' file) .

但是，而不是:

if [[ grep $check_val1 $log -ne $check_val1 || grep $check_val2 $log -ne $check_val2 ]]; then

您可以使用 grep -q :

if grep -q -e "$check_val1" -e "$check_val2" "$log"; then

根据 man grep :

-q, --quiet, --silent
         Quiet mode: suppress normal output.  grep will only search a file until a match 
         has been found, making searches potentially less expensive.