Linux Command Line And Shell Scripting – Book Review

October. 1. 2012 by lawnz –  Category: Computers, Shopping (No Comments)

Bash has improved and is very useful for a lot of tasks, many test suites from major companies are written in Bash, I also wrote test automation in Bash for my company. I bought this book “Linux Command Line And Shell Scripting – Second Edtion” on Amazon.com

http://www.amazon.com/Linux-Command-Scripting-Second-Edition/dp/1118004426/ref=sr_1_1?ie=UTF8&qid=1349152894&sr=8-1&keywords=Linux+Command+Line+And+Shell+Scripting

although most people rate this book five stars on Amazon, I have some comments:

1. it does not build the foundation for your scripting.

see how Bash work,

http://fvue.nl/wiki/Bash:_Why_use_eval_with_variable_expansion%3F

2. passing array by value is one way, isn’t passing array by reference better? for example,

a=(j k)
function test {
eval b=(\${$1[*]})
echo ${b[*]}
}
test a

note: above script and script in the book do not work for array such as (‘a b’ ‘c’ ‘d’).

3. a lot of commands are still in old style back tick, they could be $(some command)

4. after reading the whole book, you won’t understand how these two commands work,

gunzip <test.tar.gz | tar -xpf -

outs=$(expect – <<EOF
cmd1
cmd2
EOF
)

a single dash at the end of command end argument to makes the command take input from pipe or here doc.

5. this book focused on Bash, but there is nothing on hash variables which is supported in Bash version 4 released in 2009.

6. not much on bash’s built-in regular expression comparison operator “=~” which is supported since Bash version 3 released in 2004.

7. nothing about upstart jobs and run levels on Ubuntu

8. this book is huge, a lot of stuff in the book is to fill the pages, who would use the editor called Kate? : )





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