unix - Unix脚本尝试分配变量时出错？

Question

我对 Unix 非常陌生，这让我发疯。我收到此错误：

./lines: line 21: [[: grep -c *.* $3: syntax error: operand expected
(error toke                                           n is ".* $3")
./lines: line 26: [[: grep -c *.* $3: syntax error: operand expected
(error toke n is ".* $3")

运行此脚本时：

#!/bin/bash
#lines <start> <finish> <file> prints lines start-finish of file

if [[ $# != 3 ]]
then    echo "Command format: lines <starting line> <end line> <filename>"
    exit
fi

tLines='grep -c *.* $3'
start=$1
finish=$2

if [[ $finish -lt $start ]]
    then echo "$finish is less than $start. I'll go ahead and reverse those for you."
    start=$2
    finish=$1
fi

start=$((finish-start+1))

if [[ $tLines -lt $start ]] 
    then echo "$3 is only $tLines lines - that's less than $start"
    exit
fi

if [[ $tLines -lt $finish ]]
    then echo "3 is only $tLines line - that's less than $finish"
    exit
fi
head -$finish $3 | tail -$start
exit

我不知道这些错误是什么意思，在网上搜索它们并没有给我太多的洞察力。我很感激任何帮助！

Answer 1

似乎您想在这里使用命令替换：

tLines='grep -c *.* $3'

但是您使用了错误的引号。正确的是旧的反引号：

tLines=`grep -c *.* $3`

或者更新的形式：

tLines=$(grep -c *.* $3)