捕获文件，以及单独列，并添加使用某物阵列 [英] capture a file and separate columns and add sth using arrays

问题描述

我要管理我的 / etc / passwd文件并为每一列中添加姓名。

I want to manage my /etc/passwd and add names for each column..

我想从阵列中读取数据...

I want to read from array...

我试过如下bash的：

What I tried is the following bash:

#!/bin/bash

FILE="/etc/passwd"
arr=( $(awk < $FILE -F: '{print $1 $5 $6 $7}') )

for Username Realname Homedir Loginshell in "${arr[@]}"; do
    result=$(printf 'Username: %s Realname: %s Homedir: %s Loginshell: %s' "$Username" "$Realname" "$Homedir" "Loginshell")
    echo "$result"
done

但有错误：

./u.sh: line 6: syntax error near unexpected token `Realname'
./u.sh: line 6: `for Username Realname Homedir Loginshell in "${arr[@]}"; do'

第二个问题是：

我怎么能读 $文件在这样的脚本参数......因为当改剧本，如：

How can I read $FILE as an argument in such scripts...because when change the script like:

#!/bin/bash

if [ "$#" -ne "1" ]; then
    echo "Usage: `basename $0` <input-file>"
    exit 1
fi

arr=( $(awk < $1 -F: '{print $1 $2 $6 $7}') )

for Username Realname Homedir Loginshell in "${arr[@]}"; do
    result=$(printf 'Username: %s Realname: %s Homedir: %s Loginshell: %s' "$Username" "$Realname" "$Homedir" "Loginshell")
    echo "$result"
done

这将崩溃...

It would crash...

感谢

推荐答案

该方法避免了 AWK ，但使用bash的 IFS 在文件分隔字段：

This approach avoids awk but using bash's IFS to separate the fields in FILE:

FILE="/etc/passwd"
while IFS=: read Username pass uid gid Realname Homedir Loginshell; do
    result=$(printf 'Username: %s Realname: %s Homedir: %s Loginshell: %s' "$Username" "$Realname" "$Homedir" "$Loginshell")
    echo "$result"
done <"$FILE"

要提供文件名作为参数（如每题2）：

To supply the file name as an argument (as per question 2):

if [ "$#" -ne "1" ]; then
    echo "Usage: `basename $0` <input-file>"
    exit 1
fi
FILE=$1

while IFS=: read Username pass uid gid Realname Homedir Loginshell; do
    result=$(printf 'Username: %s Realname: %s Homedir: %s Loginshell: %s' "$Username" "$Realname" "$Homedir" "$Loginshell")
    echo "$result"
done <"$FILE"

如果你想使用数组，然后：

If you want to use arrays, then:

#!/bin/bash
if [ "$#" -ne "1" ]; then
    echo "Usage: `basename $0` <input-file>"
    exit 1
fi
FILE=$1

#declare -a fields
IFS=:
while read line; do
    fields=($line)
    result=$(printf 'Username: %s Realname: %s Homedir: %s Loginshell: %s' "${fields[0]}" "${fields[4]}" "${fields[5]}" "${fields[6]}")
    echo "$result"
done <"$FILE"

以上一次读取 / etc / passwd文件一行。随着 IFS 设置为一个冒号，每行中使用栏=（$线），再转换为一个数组。为了避免意外，您可能希望在执行任何庆典 code依赖前 IFS 重置为默认值在庆典的正常字分离规则。

The above reads /etc/passwd one line at a time. With IFS set to a colon, each line is then converted to an array using fields=($line). To avoid surprises, you may want to reset IFS to its default value before executing any bash code that depends on bash's normal word separation rules.

下面是企图pretty印刷输出：

Here is an attempt at pretty-printing the output:

#!/bin/bash
if [ "$#" -ne "1" ]; then
    echo "Usage: `basename $0` <input-file>"
    exit 1
fi
FILE=$1

{
echo "========:========:=======:=========="
echo "Username:Realname:Homedir:Loginshell"
echo "========:========:=======:=========="

IFS=:
while read line; do
    fields=($line)
    echo "${fields[0]}:${fields[4]}:${fields[5]}:${fields[6]}"
done < "$FILE"
} | column -nts:

在默认情况下，列分离用空白领域。然而，实名输出字段可以包含空格。因此，在-s ：选项用来使列输入使用冒号分隔的字段。为了确保标题排队的数据字段，无论是标题和数据被提交给列。

By default, column separates fields by whitespace. However, the realname output field can contain spaces. So, the -s: option is used so that column uses colon-separated fields on input. To assure that headings lined up with the data fields, both headings and data are submitted to the same instance of column.

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