本文介绍了在while循环bash脚本中读取文件的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

我有这段代码可以读取/etc/passwd的示例文件:

I've got this code which reads an example file of /etc/passwd:

#!/bin/bash

OLDIFS=$IFS
IFS=$'\n'

while read linea resto
do
        echo $linea
        echo $resto
        if [[ $(echo $linea | cut -d: -f6 | egrep -c 'al-03-04') == 1 ]]
        then
                finger $(cut -d: -f1) 2> fich
                if [[ $(egrep -c fich) == 1 ]]
                then
                        echo $(echo $linea | cut -d: -f1). Inactive user
                else
                        echo $(echo $linea | cut -d: -f1). Active user
                fi
        fi
done < <(cat fichpasswd)

IFS=$OLDIFS

这是/etc/passwd的示例文件:

and this is the example file of /etc/passwd:

jfer:x:5214:1007:Javier Lopez,,,:/home/al-03-04/jfer:/bin/bash
jperez:x:10912:1009:Juan Perez,,,:/home/al-03-04/jperez:/bin/bash
mfernan:x:10913:1009:Manuel Fernandez,,,:/home/al-02-03/mfernan:/bin/bash

问题在于while循环仅读取第一行,而忽略其他行.脚本的输出为:

The problem is that the while loop only reads the first line, ignoring the others. The script's output is:

jfer:x:5214:1007:Javier Lopez,,,:/home/al-03-04/jfer:/bin/bash

jfer. Active user

推荐答案

您可以尝试以下方法:

#!/bin/bash

FILE="test.txt"

while IFS=":" read -a data; do
  echo "${data[@]}"
  if [[ $(echo ${data[5]}|egrep -c 'al-03-04') -eq 1 ]]; then
    if [[ $(finger "${data[0]}" 2>&1) =~ "no such user" ]]; then
      echo "${data[0]}. Inactive user"
    else
      echo "${data[0]}. Active user"
    fi
  fi
done < "$FILE"

这是输出:

ineumann ~ $ cat test.txt
ineumann:x:5214:1007:Javier Lopez,,,:/home/al-03-04/jfer:/bin/bash
jperez:x:10912:1009:Juan Perez,,,:/home/al-03-04/jperez:/bin/bash
mfernan:x:10913:1009:Manuel Fernandez,,,:/home/al-02-03/mfernan:/bin/bash
ineumann ~ $ ./test.sh
ineumann x 5214 1007 Javier Lopez,,, /home/al-03-04/jfer /bin/bash
ineumann. Active user
jperez x 10912 1009 Juan Perez,,, /home/al-03-04/jperez /bin/bash
jperez. Inactive user
mfernan x 10913 1009 Manuel Fernandez,,, /home/al-02-03/mfernan /bin/bash

对脚本的一些评论:

  • 无需使用cat循环读取文件.
  • finger $(cut -d: -f1) 2> fich:cut需要输入.无需使用临时文件来捕获finger的输出(而且这不是线程安全的).
  • 当您选择正确的IFS将行分成多个部分时,无需在脚本中使用cut.对于您而言,我认为最明智的选择是:.
  • 您只能使用语法while IFS=':' read; do ...; done在循环内部更改IFS.无需用OLDIFS重新分配IFS.
  • 您还可以使用while IFS=':' read var1 var2 var3 trash; do ...; done语法来避免将数组与read -a一起使用(但是我更喜欢使用我在脚本版本中编写的数组).
  • No need to use cat to read your file in a loop.
  • finger $(cut -d: -f1) 2> fich : cut need an input. And no need to use a temporary file to catch the output of finger (moreover this is not thread safe).
  • No need to use cut in your script when you choose the right IFS to split a line in multiple parts. In your case, I think the smartest choice would be :.
  • You can change the IFS only inside the loop with the syntax while IFS=':' read; do ...; done. No need to re-assign IFS with OLDIFS.
  • You can also use the while IFS=':' read var1 var2 var3 trash; do ...; done syntax to avoid to use an array with read -a (but I'd prefer to use an array as I wrote in my version of your script).

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07-23 00:24
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