Question

我正在尝试用bash编写一个脚本来读入参数（用户名），然后通过搜索/ etc / passwd文件返回有关该用户名的信息。我不是服务器上的根，我正在编写脚本，但我不需要。这是我到目前为止的代码，但我不认为我正在使用grep命令。

#!/bin/bash
if [ $# -eq 1 ]; then #if num of args =1; then continue on
        UNAME=$1 #set arg to var UNAME
        grep UNAME=$(grep $/etc/passwd)
        if [ $UNAME == /etc/passwd ]; then #if UNAME exists then display info below
                echo "-------------------------------------------"
                echo "Username:       $(grep UNAME/etc/passwd/ $f1) "
                echo "User ID (UID):  $(grep UNAME/etc/passwd/) "
                echo "Group ID (GID): $(grep UNAME/etc/passwd/) "
                echo "User info:      $(grep UNAME/etc/passwd/) "
                echo "Home directory: $(grep UNAME/etc/passwd/) "
                echo "Command shell:  $(grep UNAME/etc/passwd/) "
                echo "-------------------------------------------"
        else #if UNAME is nonexistant then display this error message
                echo "-------------------------------------------"
                echo ""$UNAME" does not exist."
                echo "-------------------------------------------"
        fi
fi
if [ $# -eq 0 ]; then #if num of args =0; then display this
        echo "Not enough arguments provided."
        echo "USAGE: $0 <user_name> [user_name] ..."
        exit 1
fi

Answer 1

你做得太多了。 grep是您尝试进行的解析类型的错误工具。这里给出的解决方案非常草率，因为它为您查询的每个用户读取一次passwd文件，而不是一次性报告所有内容，但这并非不合理：

#!/bin/sh

for UNAME; do
        while IFS=: read login passwd uid gid name home shell; do
                if test "$login" = "$UNAME"; then
                        echo "-------------------------------------------"
                        echo "Username:       $login"
                        echo "User ID (UID):  $uid"
                        echo "Group ID (GID): $gid"
                        echo "User info:      $name"
                        echo "Home directory: $home"
                        echo "Command shell:  $shell"
                        echo "-------------------------------------------"
                        continue 2
                fi
        done < /etc/passwd
        echo "No entry for user $UNAME" >&2
done

Answer 2

在我得到解释之前，我将编写你的剧本：

cat ./test.sh 
#!/bin/bash

UNAME=${1} #set arg to var UNAME
if [ -z ${UNAME} ]; then #if no argument is provided; then display this
    echo "Not enough arguments provided."
    echo "USAGE: $0 <user_name>" 
    exit 1
fi
if grep ${UNAME} /etc/passwd >/dev/null; then #if UNAME exists then display info below
    echo "-------------------------------------------"
    echo "Username:       $(awk -F ':' -v uname=${UNAME} '$0 ~ uname {print $1}' /etc/passwd)"
    echo "User ID (UID):  $(awk -F ':' -v uname=${UNAME} '$0 ~ uname {print $3}' /etc/passwd)"
    echo "Group ID (GID): $(awk -F ':' -v uname=${UNAME} '$0 ~ uname {print $4}' /etc/passwd)"
    echo "User info:      $(awk -F ':' -v uname=${UNAME} '$0 ~ uname {print $5}' /etc/passwd)"
    echo "Home directory: $(awk -F ':' -v uname=${UNAME} '$0 ~ uname {print $6}' /etc/passwd)"
    echo "Command shell:  $(awk -F ':' -v uname=${UNAME} '$0 ~ uname {print $7}' /etc/passwd)"
    echo "-------------------------------------------"
else #if UNAME is nonexistant then display this error message
    echo "-------------------------------------------"
    echo "\"${UNAME}\" does not exist."
    echo "-------------------------------------------"
fi

说明：

if可以直接使用grep来检查是否存在你在passwd中的论点
UNAME=是如何分配参数的，而不是调用 - 用$ - 调用它们 - 例如$UNAME
/etc/passwd是绝对文件名，因此不是参数 $/etc/passwd并不意味着要打击
argument=$(any old bash command)告诉bash你想要的将“any old bash command”的输出分配给“argument”，所以$() 必须包含一个命令，其中包含要分配的“参数”的输出任何东西。
>/dev/null将grep的输出发送到废纸篓，因为我们只关心它是否成功，以便if知道该怎么做
grep的工作方式如下：grep <the thing you want to find> <file>（请注意，如果要在搜索中包含空格，空格很重要并使用“”）
要获取特定字段，awk更有用。 awk -F':'告诉awk我希望:定义我的字段分隔符; -v uname=${UNAME}将我的论点传递给awk;在awk中，$0 ~ uname检查我的参数行（如grep）;并且{print $1}打印第一个字段，依此类推

还要考虑部分匹配的限制。例如，如果我有一个用户JSmith和Smith，搜索Smith将返回两者。这可以通过正则表达式来解决，但会给脚本增加很多复杂性。

这是一个使用更轻的awk的版本，可以使用多个参数：

#!/bin/bash
for username; do
    if grep ${username} /etc/passwd >/dev/null; then #if username exists then display info below
        echo "---------------------------------------"
        awk -F':' -v uname="${username}" '\
            $0 ~ uname \
            {print " Username:         "$1\
                "\n User ID (UID):    "$3\
                "\n Group ID (GID):   "$4\
                "\n User info:        "$5\
                "\n Home directory:   "$6\
                "\n Command shell:    "$7}' /etc/passwd
        echo "---------------------------------------"
    else #if username is nonexistant then display this error message
        echo "---------------------------------------"
        echo "\"${username}\" does not exist."
        echo "---------------------------------------"
    fi
done

if [ -z ${1} ]; then #if no argument is provided; then display this
    echo " Not enough arguments provided."
    echo " USAGE: $0 <user name>" 
    exit 1
fi

*感谢William Pursell解释for循环

Answer 3

阅读passwd等数据库的最佳工具是getent。这将从名称服务交换机库支持的数据库中获取条目。如果您确实需要限制阅读文件数据库，可以告诉getent将files数据库与-s files一起使用。

您的代码不必要很长。获取记录并将其解析为多个变量就足够了。

#!/bin/bash
if [ $# -eq 1 ]; then #if num of args =1; then continue on
    if IFS=: read username ignore uid gid gecos home shell < <(getent -s files passwd $1); then
                echo "-------------------------------------------"
                echo "Username:       $username"
                echo "User ID (UID):  $uid"
                echo "Group ID (GID): $gid"
                echo "User info:      $gecos"
                echo "Home directory: $home"
                echo "Command shell:  $shell"
                echo "-------------------------------------------"
        else #if $1 is nonexistant then display this error message
                echo "-------------------------------------------"
                echo "'$1' does not exist."
                echo "-------------------------------------------"
        fi
fi
if [ $# -eq 0 ]; then #if num of args =0; then display this
        echo "Not enough arguments provided."
        echo "USAGE: $0 <user_name> [user_name] ..."
        exit 1
fi

bash脚本grep etc文件以获取用户信息

3 个答案: