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4 artificial intelligence trends to watch
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||||
Translating by Wuod3n
|
||||
======
|
||||
|
||||
|
||||
|
||||
However much your IT operation is using [artificial intelligence][1] today, expect to be doing more with it in 2018. Even if you have never dabbled in AI projects, this may be the year talk turns into action, says David Schatsky, managing director at [Deloitte][2]. "The number of companies doing something with AI is on track to rise," he says.
|
||||
|
||||
Check out his AI predictions for the coming year:
|
||||
|
||||
### 1. Expect more enterprise AI pilot projects
|
||||
|
||||
Many of today's off-the-shelf applications and platforms that companies already routinely use incorporate AI. "But besides that, a growing number of companies are experimenting with machine learning or natural language processing to solve particular problems or help understand their data, or automate internal processes, or improve their own products and services," Schatsky says.
|
||||
|
||||
**[ What IT jobs will be hot in the AI age? See our related article, [8 emerging AI jobs for IT pros][3]. ]**
|
||||
|
||||
"Beyond that, the intensity with which companies are working with AI will rise," he says. "Companies that are early adopters already mostly have five or fewer projects underway, but we think that number will rise to having 10 or more pilots underway." One reason for this prediction, he says, is that AI technologies are getting better and easier to use.
|
||||
|
||||
### 2. AI will help with data science talent crunch
|
||||
|
||||
Talent is a huge problem in data science, where most large companies are struggling to hire the data scientists they need. AI can take up some of the load, Schatsky says. "The practice of data science is increasingly automatable with tools offered both by startups and large, established technology vendors," he says. A lot of data science work is repetitive and tedious, and ripe for automation, he explains. "Data scientists aren't going away, but they're going to get much more productive. So a company that can only do a few data science projects without automation will be able to do much more with automation, even if it can't hire any more data scientists."
|
||||
|
||||
### 3. Synthetic data models will ease bottlenecks
|
||||
|
||||
Before you can train a machine learning model, you have to get the data to train it on, Schatsky notes. That's not always easy. "That's often a business bottleneck, not a production bottleneck," he says. In some cases you can't get the data because of regulations governing things like health records and financial information.
|
||||
|
||||
Synthetic data models can take a smaller set of data and use it to generate the larger set that may be needed, he says. "If you used to need 10,000 data points to train a model but could only get 2,000, you can now generate the missing 8,000 and go ahead and train your model."
|
||||
|
||||
### 4. AI decision-making will become more transparent
|
||||
|
||||
One of the business problems with AI is that it often operates as a black box. That is, once you train a model, it will spit out answers that you can't necessarily explain. "Machine learning can automatically discover patterns in data that a human can't see because it's too much data or too complex," Schatsky says. "Having discovered these patterns, it can make predictions about new data it hasn't seen."
|
||||
|
||||
The problem is that sometimes you really do need to know the reasons behind an AI finding or prediction. "You feed in a medical image and the model says, based on the data you've given me, there's a 90 percent chance that there's a tumor in this image," Schatsky says. "You say, 'Why do you think so?' and the model says, 'I don't know, that's what the data would suggest.'"
|
||||
|
||||
If you follow that data, you're going to have to do exploratory surgery on a patient, Schatsky says. That's a tough call to make when you can't explain why. "There are a lot of situations where even though the model produces very accurate results, if it can't explain how it got there, nobody wants to trust it."
|
||||
|
||||
There are also situations where because of regulations, you literally can't use data that you can't explain. "If a bank declines a loan application, it needs to be able to explain why," Schatsky says. "That's a regulation, at least in the U.S. Traditionally, a human underwriter makes that call. A machine learning model could be more accurate, but if it can't explain its answer, it can't be used."
|
||||
|
||||
Most algorithms were not designed to explain their reasoning. "So researchers are finding clever ways to get AI to spill its secrets and explain what variables make it more likely that this patient has a tumor," he says. "Once they do that, a human can look at the answers and see why it came to that conclusion."
|
||||
|
||||
That means AI findings and decisions can be used in many areas where they can't be today, he says. "That will make these models more trustworthy and more usable in the business world."
|
||||
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://enterprisersproject.com/article/2018/1/4-ai-trends-watch
|
||||
|
||||
作者：[Minda Zetlin][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://enterprisersproject.com/user/minda-zetlin
|
||||
[1]:https://enterprisersproject.com/tags/artificial-intelligence
|
||||
[2]:https://www2.deloitte.com/us/en.html
|
||||
[3]:https://enterprisersproject.com/article/2017/12/8-emerging-ai-jobs-it-pros?sc_cid=70160000000h0aXAAQ
|
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@ -1,249 +0,0 @@
|
||||
How To Debug a Bash Shell Script Under Linux or UNIX
|
||||
======
|
||||
From my mailbag:
|
||||
**I wrote a small hello world script. How can I Debug a bash shell scripts running on a Linux or Unix like systems?**
|
||||
It is the most common question asked by new sysadmins or Linux/UNIX user. Shell scripting debugging can be a tedious job (read as not easy). There are various ways to debug a shell script.
|
||||
|
||||
You need to pass the -x or -v argument to bash shell to walk through each line in the script.
|
||||
|
||||
[![How to debug a bash shell script on Linux or Unix][1]][1]
|
||||
|
||||
Let us see how to debug a bash script running on Linux and Unix using various methods.
|
||||
|
||||
### -x option to debug a bash shell script
|
||||
|
||||
Run a shell script with -x option.
|
||||
```
|
||||
$ bash -x script-name
|
||||
$ bash -x domains.sh
|
||||
```
|
||||
|
||||
### Use of set builtin command
|
||||
|
||||
Bash shell offers debugging options which can be turn on or off using the [set command][2]:
|
||||
|
||||
* **set -x** : Display commands and their arguments as they are executed.
|
||||
* **set -v** : Display shell input lines as they are read.
|
||||
|
||||
|
||||
|
||||
You can use above two command in shell script itself:
|
||||
```
|
||||
#!/bin/bash
|
||||
clear
|
||||
|
||||
# turn on debug mode
|
||||
set -x
|
||||
for f in *
|
||||
do
|
||||
file $f
|
||||
done
|
||||
# turn OFF debug mode
|
||||
set +x
|
||||
ls
|
||||
# more commands
|
||||
```
|
||||
|
||||
You can replace the [standard Shebang][3] line:
|
||||
`#!/bin/bash`
|
||||
with the following (for debugging) code:
|
||||
`#!/bin/bash -xv`
|
||||
|
||||
### Use of intelligent DEBUG function
|
||||
|
||||
First, add a special variable called _DEBUG. Set _DEBUG to 'on' when you need to debug a script:
|
||||
`_DEBUG="on"`
|
||||
|
||||
Put the following function at the beginning of the script:
|
||||
```
|
||||
function DEBUG()
|
||||
{
|
||||
[ "$_DEBUG" == "on" ] && $@
|
||||
}
|
||||
```
|
||||
|
||||
function DEBUG() { [ "$_DEBUG" == "on" ] && $@ }
|
||||
|
||||
Now wherever you need debugging simply use the DEBUG function as follows:
|
||||
`DEBUG echo "File is $filename"`
|
||||
OR
|
||||
```
|
||||
DEBUG set -x
|
||||
Cmd1
|
||||
Cmd2
|
||||
DEBUG set +x
|
||||
```
|
||||
|
||||
When done with debugging (and before moving your script to production) set _DEBUG to 'off'. No need to delete debug lines.
|
||||
`_DEBUG="off" # set to anything but not to 'on'`
|
||||
|
||||
Sample script:
|
||||
```
|
||||
#!/bin/bash
|
||||
_DEBUG="on"
|
||||
function DEBUG()
|
||||
{
|
||||
[ "$_DEBUG" == "on" ] && $@
|
||||
}
|
||||
|
||||
DEBUG echo 'Reading files'
|
||||
for i in *
|
||||
do
|
||||
grep 'something' $i > /dev/null
|
||||
[ $? -eq 0 ] && echo "Found in $i file"
|
||||
done
|
||||
DEBUG set -x
|
||||
a=2
|
||||
b=3
|
||||
c=$(( $a + $b ))
|
||||
DEBUG set +x
|
||||
echo "$a + $b = $c"
|
||||
```
|
||||
|
||||
Save and close the file. Run the script as follows:
|
||||
`$ ./script.sh`
|
||||
Output:
|
||||
```
|
||||
Reading files
|
||||
Found in xyz.txt file
|
||||
+ a=2
|
||||
+ b=3
|
||||
+ c=5
|
||||
+ DEBUG set +x
|
||||
+ '[' on == on ']'
|
||||
+ set +x
|
||||
2 + 3 = 5
|
||||
|
||||
```
|
||||
|
||||
Now set DEBUG to off (you need to edit the file):
|
||||
`_DEBUG="off"`
|
||||
Run script:
|
||||
`$ ./script.sh`
|
||||
Output:
|
||||
```
|
||||
Found in xyz.txt file
|
||||
2 + 3 = 5
|
||||
|
||||
```
|
||||
|
||||
Above is a simple but quite effective technique. You can also try to use DEBUG as an alias instead of function.
|
||||
|
||||
### Debugging Common Bash Shell Scripting Errors
|
||||
|
||||
Bash or sh or ksh gives various error messages on screen and in many case the error message may not provide detailed information.
|
||||
|
||||
#### Skipping to apply execute permission on the file
|
||||
|
||||
When you [write your first hello world bash shell script][4], you might end up getting an error that read as follows:
|
||||
`bash: ./hello.sh: Permission denied`
|
||||
Set permission using chmod command:
|
||||
```
|
||||
$ chmod +x hello.sh
|
||||
$ ./hello.sh
|
||||
$ bash hello.sh
|
||||
```
|
||||
|
||||
#### End of file unexpected Error
|
||||
|
||||
If you are getting an End of file unexpected error message, open your script file and and make sure it has both opening and closing quotes. In this example, the echo statement has an opening quote but no closing quote:
|
||||
```
|
||||
#!/bin/bash
|
||||
|
||||
|
||||
...
|
||||
....
|
||||
|
||||
|
||||
echo 'Error: File not found
|
||||
^^^^^^^
|
||||
missing quote
|
||||
```
|
||||
|
||||
Also make sure you check for missing parentheses and braces ({}):
|
||||
```
|
||||
#!/bin/bash
|
||||
.....
|
||||
[ ! -d $DIRNAME ] && { echo "Error: Chroot dir not found"; exit 1;
|
||||
^^^^^^^^^^^^^
|
||||
missing brace }
|
||||
...
|
||||
```
|
||||
|
||||
#### Missing Keywords Such As fi, esac, ;;, etc.
|
||||
|
||||
If you missed ending keyword such as fi or ;; you will get an error such as as "xxx unexpected". So make sure all nested if and case statements ends with proper keywords. See bash man page for syntax requirements. In this example, fi is missing:
|
||||
```
|
||||
#!/bin/bash
|
||||
echo "Starting..."
|
||||
....
|
||||
if [ $1 -eq 10 ]
|
||||
then
|
||||
if [ $2 -eq 100 ]
|
||||
then
|
||||
echo "Do something"
|
||||
fi
|
||||
|
||||
for f in $files
|
||||
do
|
||||
echo $f
|
||||
done
|
||||
|
||||
# note fi is missing
|
||||
```
|
||||
|
||||
#### Moving or editing shell script on Windows or Unix boxes
|
||||
|
||||
Do not create the script on Linux/Unix and move to Windows. Another problem is editing the bash shell script on Windows 10 and move/upload to Unix server. It will result in an error like command not found due to the carriage return (DOS CR-LF). You [can convert DOS newlines CR-LF to Unix/Linux format using][5] the following syntax:
|
||||
`dos2unix my-script.sh`
|
||||
|
||||
### Tip 1 - Send Debug Message To stderr
|
||||
|
||||
[Standard error][6] is the default error output device, which is used to write all system error messages. So it is a good idea to send messages to the default error device:
|
||||
```
|
||||
# Write error to stdout
|
||||
echo "Error: $1 file not found"
|
||||
#
|
||||
# Write error to stderr (note 1>&2 at the end of echo command)
|
||||
#
|
||||
echo "Error: $1 file not found" 1>&2
|
||||
```
|
||||
|
||||
### Tip 2 - Turn On Syntax Highlighting when using vim text editor
|
||||
|
||||
Most modern text editors allows you to set syntax highlighting option. This is useful to detect syntax and prevent common errors such as opening or closing quote. You can see bash script in different colors. This feature eases writing in a shell script structures and syntax errors are visually distinct. Highlighting does not affect the meaning of the text itself; it's made only for you. In this example, vim syntax highlighting is used for my bash script:
|
||||
[![How To Debug a Bash Shell Script Under Linux or UNIX Using Vim Syntax Highlighting Feature][7]][7]
|
||||
|
||||
### Tip 3 - Use shellcheck to lint script
|
||||
|
||||
[ShellCheck is a static analysis tool for shell scripts][8]. One can use it to finds bugs in your shell scripts. It is written in Haskell. You can find warnings and suggestions for bash/sh shell scripts with this tool. Let us see how to install and use ShellCheck on a Linux or Unix-like system to enhance your shell scripts, avoid errors and productivity.
|
||||
|
||||
|
||||
### About the author
|
||||
|
||||
Posted by:
|
||||
|
||||
The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on [Twitter][9], [Facebook][10], [Google+][11].
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.cyberciti.biz/tips/debugging-shell-script.html
|
||||
|
||||
作者：[Vivek Gite][a]
|
||||
译者：[译者ID](https://github.com/译者ID)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.cyberciti.biz
|
||||
[1]:https://www.cyberciti.biz/tips/wp-content/uploads/2007/01/How-to-debug-a-bash-shell-script-on-Linux-or-Unix.jpg
|
||||
[2]:https://bash.cyberciti.biz/guide/Set_command
|
||||
[3]:https://bash.cyberciti.biz/guide/Shebang
|
||||
[4]:https://www.cyberciti.biz/faq/hello-world-bash-shell-script/
|
||||
[5]:https://www.cyberciti.biz/faq/howto-unix-linux-convert-dos-newlines-cr-lf-unix-text-format/
|
||||
[6]:https://bash.cyberciti.biz/guide/Standard_error
|
||||
[7]:https://www.cyberciti.biz/media/new/tips/2007/01/bash-vim-debug-syntax-highlighting.png
|
||||
[8]:https://www.cyberciti.biz/programming/improve-your-bashsh-shell-script-with-shellcheck-lint-script-analysis-tool/
|
||||
[9]:https://twitter.com/nixcraft
|
||||
[10]:https://facebook.com/nixcraft
|
||||
[11]:https://plus.google.com/+CybercitiBiz
|
||||
@ -1,3 +1,5 @@
|
||||
translating by ucasFL
|
||||
|
||||
How does gdb work?
|
||||
============================================================
|
||||
|
||||
|
||||
@ -1,3 +1,5 @@
|
||||
translating by ucasFL
|
||||
|
||||
How to generate webpages using CGI scripts
|
||||
======
|
||||
Back in the stone age of the Internet when I first created my first business website, life was good.
|
||||
|
||||
@ -1,3 +1,5 @@
|
||||
translating by ucasFL
|
||||
|
||||
How does gdb call functions?
|
||||
============================================================
|
||||
|
||||
|
||||
@ -1,3 +1,5 @@
|
||||
translating by ucasFL
|
||||
|
||||
Linux mkdir Command Explained for Beginners (with examples)
|
||||
======
|
||||
|
||||
|
||||
@ -0,0 +1,67 @@
|
||||
4个需要注意的人工智能趋势
|
||||
======
|
||||
|
||||
|
||||
|
||||
|
||||
无论你的IT业务现在使用了多少[人工智能][1]，预计你将会在2018年使用更多。即便你从来没有涉猎过AI项目，这也可能是谈论转变为行动的一年，[德勤][2]董事总经理David Schatsky说。他说：“与AI开展合作的公司数量正在上升。
|
||||
|
||||
看看他对未来一年的AI预测：
|
||||
|
||||
###1.期待更多的企业AI试点项目
|
||||
公司已经将经常使用的许多现成的应用程序和平台都将AI结合在一起。 Schatsky说：“除此之外，越来越多的公司正在试验机器学习或自然语言处理来解决特定的问题，或者帮助理解他们的数据，或者使内部流程自动化，或者改进他们自己的产品和服务。
|
||||
|
||||
**[在AI时代，哪些IT工作会变得热门？ 请参阅我们的相关文章，, [为专业IT人士提供的8个新兴AI工作][3]. ]**
|
||||
|
||||
他说：“除此之外，公司与人工智能的合作强度将会上升。”“早期采纳的公司已经有五个或更少的项目正在进行中，但是我们认为这个数字会上升到10个或有更多正在进行的计划。” 他说，这个预测的一个原因是人工智能技术正在变得越来越好，也越来越容易使用。
|
||||
|
||||
###2.人工智能将缓解数据科学人才紧缺的现状
|
||||
人才是数据科学中的一个大问题，大多数大公司都在努力聘用他们所需要的数据科学家。 Schatsky说，AI可以承担一些负担。 他说：“数据科学的实践，逐渐成为由创业公司和大型成熟的技术供应商提供的自动化的工具。 他解释说，大量的数据科学工作是重复的，乏味的，自动化的时机已经成熟。 “数据科学家不会离开，但他们将会获得更高的生产力，所以一家只能做一些数据科学项目而没有自动化的公司将能够使用自动化来做更多的事情，虽然它不能雇用更多的数据科学家”。
|
||||
|
||||
###3.合成数据模型将缓解瓶颈
|
||||
Schatsky指出，在你训练机器学习模型之前，你必须得到数据来训练它。 这并不容易，他说：“这通常是一个商业瓶颈，而不是生产瓶颈。 在某些情况下，由于有关健康记录和财务信息的规定，你无法获取数据。
|
||||
|
||||
他说，合成数据模型可以采集一小部分数据，并用它来生成可能需要的较大集合。 “如果你以前需要10000个数据点来训练一个模型，但是只能得到2000个，那么现在就可以产生缺少的8000个数据点，然后继续训练你的模型。”
|
||||
|
||||
###4.人工智能决策将变得更加透明
|
||||
AI的业务问题之一就是它经常作为一个黑匣子来操作。 也就是说，一旦你训练了一个模型，它就会吐出你不能解释的答案。 Schatsky说：“机器学习可以自动发现人类无法看到的数据模式，因为数据太多或太复杂。 “发现了这些模式后，它可以预测未见的新数据。”
|
||||
|
||||
问题是，有时你确实需要知道AI发现或预测背后的原因。 Schatsky说：“以医学图像为例子来说，模型说根据你给我的数据，这个图像中有90％的可能性是肿瘤。 “你说，你为什么这么认为？ 模型说：“我不知道，这是数据给的建议。”
|
||||
|
||||
Schatsky说，如果你遵循这些数据，你将不得不对患者进行探查手术。 当你无法解释为什么时，这是一个艰难的请求。 “但在很多情况下，即使模型产生了非常准确的结果，如果不能解释为什么，也没有人愿意相信它。”
|
||||
|
||||
还有一些情况是由于规定，你确实不能使用你无法解释的数据。 Schatsky说：“如果一家银行拒绝贷款申请，就需要能够解释为什么。 ”这是一个法规，至少在美国。传统上来说，人类的保险公司是这样称呼的，一个机器学习模式可能会更准确，但如果不能解释它的答案，就不能使用。
|
||||
|
||||
大多数算法不是为了解释他们的推理而设计的。 他说：“所以研究人员正在找到聪明的方法来让AI泄漏秘密，并解释哪些变量使得这个病人更可能患有肿瘤。 “一旦他们这样做，一个人可以发现答案，看看为什么会有这样的结论。”
|
||||
|
||||
他说，这意味着人工智能的发现和决定可以用在许多今天不可能的领域。 “这将使这些模型更加值得信赖，在商业世界中更具可用性。”
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://enterprisersproject.com/article/2018/1/4-ai-trends-watch
|
||||
|
||||
作者：[Minda Zetlin][a]
|
||||
译者：[Wuod3n](https://github.com/Wuod3n)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://enterprisersproject.com/user/minda-zetlin
|
||||
[1]:https://enterprisersproject.com/tags/artificial-intelligence
|
||||
[2]:https://www2.deloitte.com/us/en.html
|
||||
[3]:https://enterprisersproject.com/article/2017/12/8-emerging-ai-jobs-it-pros?sc_cid=70160000000h0aXAAQ
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
@ -0,0 +1,246 @@
|
||||
如何在 Linux 或者 UNIX 下调试 Bash Shell 脚本
|
||||
======
|
||||
来自我的邮箱：
|
||||
**我写了一个你好世界的小脚本。我如何能调试运行在 Linux 或者类 UNIX 的系统上的 bash shell 脚本呢？**
|
||||
这是 Linux / Unix 系统管理员或新用户最常问的问题。shell 脚本调试可能是一项繁琐的工作（不容易阅读）。调试 shell 脚本有多种方法。
|
||||
|
||||
您需要传递 -X 或 -V 参数，以在 bash shell 中浏览每行代码。
|
||||
|
||||
[![如何在 Linux 或者 UNIX 下调试 Bash Shell 脚本][1]][1]
|
||||
|
||||
让我们看看如何使用各种方法调试 Linux 和 UNIX 上运行的脚本。
|
||||
|
||||
```
|
||||
### -x 选项来调试脚本
|
||||
|
||||
用 -x 选项来运行脚本
|
||||
```
|
||||
$ bash -x script-name
|
||||
$ bash -x domains.sh
|
||||
```
|
||||
|
||||
### 使用 set 内置命令
|
||||
|
||||
bash shell 提供调试选项，可以打开或关闭使用 [set 命令][2]：
|
||||
|
||||
* **set -x** : 显示命令及其执行时的参数。
|
||||
* **set -v** : 显示 shell 输入行作为它们读取的
|
||||
|
||||
可以在shell脚本本身中使用上面的两个命令：
|
||||
```
|
||||
#!/bin/bash
|
||||
clear
|
||||
|
||||
# turn on debug mode
|
||||
set -x
|
||||
for f in *
|
||||
do
|
||||
file $f
|
||||
done
|
||||
# turn OFF debug mode
|
||||
set +x
|
||||
ls
|
||||
# more commands
|
||||
```
|
||||
|
||||
你可以代替 [标准 Shebang][3] 行：
|
||||
`#!/bin/bash`
|
||||
用一下代码（用于调试）：
|
||||
`#!/bin/bash -xv`
|
||||
|
||||
### 使用智能调试功能
|
||||
|
||||
首先添加一个叫做 _DEBUG 的特殊变量。当你需要调试脚本的时候，设置 _DEBUG 为 'on'：
|
||||
`_DEBUG="on"`
|
||||
|
||||
|
||||
在脚本的开头放置以下函数：
|
||||
```
|
||||
function DEBUG()
|
||||
{
|
||||
[ "$_DEBUG" == "on" ] && $@
|
||||
}
|
||||
```
|
||||
|
||||
function DEBUG() { [ "$_DEBUG" == "on" ] && $@ }
|
||||
|
||||
现在，只要你需要调试，只需使用 DEBUG 函数如下：
|
||||
`DEBUG echo "File is $filename"`
|
||||
或者
|
||||
```
|
||||
DEBUG set -x
|
||||
Cmd1
|
||||
Cmd2
|
||||
DEBUG set +x
|
||||
```
|
||||
|
||||
当调试完（在移动你的脚本到生产环境之前）设置 _DEBUG 为 'off'。不需要删除调试行。
|
||||
`_DEBUG="off" # 设置为非 'on' 的任何字符`
|
||||
|
||||
|
||||
示例脚本：
|
||||
```
|
||||
#!/bin/bash
|
||||
_DEBUG="on"
|
||||
function DEBUG()
|
||||
{
|
||||
[ "$_DEBUG" == "on" ] && $@
|
||||
}
|
||||
|
||||
DEBUG echo 'Reading files'
|
||||
for i in *
|
||||
do
|
||||
grep 'something' $i > /dev/null
|
||||
[ $? -eq 0 ] && echo "Found in $i file"
|
||||
done
|
||||
DEBUG set -x
|
||||
a=2
|
||||
b=3
|
||||
c=$(( $a + $b ))
|
||||
DEBUG set +x
|
||||
echo "$a + $b = $c"
|
||||
```
|
||||
|
||||
保存并关闭文件。运行脚本如下：
|
||||
`$ ./script.sh`
|
||||
输出:
|
||||
```
|
||||
Reading files
|
||||
Found in xyz.txt file
|
||||
+ a=2
|
||||
+ b=3
|
||||
+ c=5
|
||||
+ DEBUG set +x
|
||||
+ '[' on == on ']'
|
||||
+ set +x
|
||||
2 + 3 = 5
|
||||
|
||||
```
|
||||
|
||||
现在设置 DEBUG 为关闭（你需要编辑文件）：
|
||||
`_DEBUG="off"`
|
||||
运行脚本:
|
||||
`$ ./script.sh`
|
||||
输出:
|
||||
```
|
||||
Found in xyz.txt file
|
||||
2 + 3 = 5
|
||||
|
||||
```
|
||||
|
||||
以上是一个简单但非常有效的技术。还可以尝试使用 DEBUG 作为别名替代函数。
|
||||
|
||||
### 调试 Bash Shell 的常见错误
|
||||
|
||||
Bash 或者 sh 或者 ksh 在屏幕上给出各种错误信息，在很多情况下，错误信息可能不提供详细的信息。
|
||||
|
||||
#### 跳过在文件上应用执行权限
|
||||
When you [write your first hello world bash shell script][4], you might end up getting an error that read as follows:
|
||||
当你 [编写你的第一个 hello world 脚本][4],您可能会得到一个错误，如下所示：
|
||||
`bash: ./hello.sh: Permission denied`
|
||||
设置权限使用 chmod 命令:
|
||||
```
|
||||
$ chmod +x hello.sh
|
||||
$ ./hello.sh
|
||||
$ bash hello.sh
|
||||
```
|
||||
|
||||
#### 文件结束时发生意外的错误
|
||||
|
||||
如果您收到文件结束意外错误消息，请打开脚本文件，并确保它有打开和关闭引号。在这个例子中，echo 语句有一个开头引号，但没有结束引号：
|
||||
```
|
||||
#!/bin/bash
|
||||
|
||||
|
||||
...
|
||||
....
|
||||
|
||||
|
||||
echo 'Error: File not found
|
||||
^^^^^^^
|
||||
missing quote
|
||||
```
|
||||
|
||||
还要确保你检查缺少的括号和大括号 ({}):
|
||||
```
|
||||
#!/bin/bash
|
||||
.....
|
||||
[ ! -d $DIRNAME ] && { echo "Error: Chroot dir not found"; exit 1;
|
||||
^^^^^^^^^^^^^
|
||||
missing brace }
|
||||
...
|
||||
```
|
||||
|
||||
#### 丢失像 fi，esac，;; 等关键字。
|
||||
如果你缺少了结尾的关键字，如 fi 或 ;; 你会得到一个错误，如 “XXX 意外”。因此，确保所有嵌套的 if 和 case 语句以适当的关键字结束。有关语法要求的页面。在本例中，缺少 fi：
|
||||
```
|
||||
#!/bin/bash
|
||||
echo "Starting..."
|
||||
....
|
||||
if [ $1 -eq 10 ]
|
||||
then
|
||||
if [ $2 -eq 100 ]
|
||||
then
|
||||
echo "Do something"
|
||||
fi
|
||||
|
||||
for f in $files
|
||||
do
|
||||
echo $f
|
||||
done
|
||||
|
||||
# 注意 fi 已经丢失
|
||||
```
|
||||
|
||||
#### 在 Windows 或 UNIX 框中移动或编辑 shell 脚本
|
||||
|
||||
不要在 Linux 上创建脚本并移动到 Windows。另一个问题是编辑 Windows 10上的 shell 脚本并将其移动到 UNIX 服务器上。这将导致一个错误的命令没有发现由于回车返回（DOS CR-LF）。你可以 [将 DOS 换行转换为 CR-LF 的Unix/Linux 格式][5] 使用下列命令：
|
||||
`dos2unix my-script.sh`
|
||||
|
||||
### 提示1 - 发送调试信息输出到标准错误
|
||||
[标准错误] 是默认错误输出设备，用于写所有系统错误信息。因此，将消息发送到默认的错误设备是个好主意：
|
||||
```
|
||||
# 写错误到标准输出
|
||||
echo "Error: $1 file not found"
|
||||
#
|
||||
# 写错误到标准错误（注意 1>&2 在 echo 命令末尾）
|
||||
#
|
||||
echo "Error: $1 file not found" 1>&2
|
||||
```
|
||||
|
||||
### 提示2 - 在使用 vim 文本编辑器时，打开语法高亮。
|
||||
大多数现代文本编辑器允许设置语法高亮选项。这对于检测语法和防止常见错误如打开或关闭引号非常有用。你可以在不同的颜色中看到。这个特性简化了 shell 脚本结构中的编写，语法错误在视觉上截然不同。强调不影响文本本身的意义，它只为你编写。在这个例子中，我的脚本使用了 vim 语法高亮：
|
||||
[!如何调试 Bash Shell 脚本，在 Linux 或者 UNIX 使用 Vim 语法高亮特性][7]][7]
|
||||
|
||||
### 提示3 - 使用 shellcheck 检查脚本
|
||||
[shellcheck 是一个用于静态分析 shell 脚本的工具][8]。可以使用它来查找 shell 脚本中的错误。这是用 Haskell 编写的。您可以使用这个工具找到警告和建议。让我们看看如何在 Linux 或 类UNIX 系统上安装和使用 shellcheck 来改善你的 shell 脚本，避免错误和高效。
|
||||
|
||||
### 关于作者
|
||||
发表者：
|
||||
|
||||
作者是 nixCraft 创造者，一个经验丰富的系统管理员和一个练习 Linux 操作系统/ UNIX shell 脚本的教练。他曾与全球客户和各种行业，包括 IT，教育，国防和空间研究，以及非营利部门。跟随他 [推特][9]，[脸谱网][10]，[谷歌+ ][11]。
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
|
||||
via: https://www.cyberciti.biz/tips/debugging-shell-script.html
|
||||
|
||||
作者：[Vivek Gite][a]
|
||||
译者：[zjon](https://github.com/zjon)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://www.cyberciti.biz
|
||||
[1]:https://www.cyberciti.biz/tips/wp-content/uploads/2007/01/How-to-debug-a-bash-shell-script-on-Linux-or-Unix.jpg
|
||||
[2]:https://bash.cyberciti.biz/guide/Set_command
|
||||
[3]:https://bash.cyberciti.biz/guide/Shebang
|
||||
[4]:https://www.cyberciti.biz/faq/hello-world-bash-shell-script/
|
||||
[5]:https://www.cyberciti.biz/faq/howto-unix-linux-convert-dos-newlines-cr-lf-unix-text-format/
|
||||
[6]:https://bash.cyberciti.biz/guide/Standard_error
|
||||
[7]:https://www.cyberciti.biz/media/new/tips/2007/01/bash-vim-debug-syntax-highlighting.png
|
||||
[8]:https://www.cyberciti.biz/programming/improve-your-bashsh-shell-script-with-shellcheck-lint-script-analysis-tool/
|
||||
[9]:https://twitter.com/nixcraft
|
||||
[10]:https://facebook.com/nixcraft
|
||||
[11]:https://plus.google.com/+CybercitiBiz
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user