linux - bash 文件 Linux Ubuntu

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我不知道为什么我的 bash 文件在 Linux Ubuntu 中不起作用。

#!/bin/bash`   
echo -n "Write user name : "
read NAME
cd
if grep -c "$NAME" /etc/passwd -eq 0; then
  echo "$NAME doesn't esist"
else
  echo "$NAME already esist"
fi`

它给出了错误:

$ bash ./name.sh 
Write user name : root
grep: root: No such file or directory
/etc/passwd:3
grep: 0: No such file or directory

Answer 1

代码没有在子 shell 中执行 grep，并且 if 条件需要用方括号括起来。

#!/bin/bash

echo -n "Write user name : "
read NAME
cd
if [ `grep -c "$NAME" /etc/passwd` -eq 0 ]; then
  echo "$NAME doesn't esist"
else
  echo "$NAME" already esist
fi

输出:

$ bash ./name.sh
Write user name : root
root already esist
$ bash ./name.sh
Write user name : ddd
ddd doesn't esist