Bash script: sored string with variables

bastl · 05-02-2017, 04:05 PM

Hello
I have a strings stored in a array with

Code:

readarray -t usr_opt < usr.file

so I do now assign and check these options:

Code:

...
eval i_dir=("${usr_opt[6]}") # holds a directory
eval copt=("${usr_opt[42]}") # are user options: --opt1=$idir --opt2 --opt3="hello"

now
eval copt=("${usr_opt[42]}")
truncates copt after --opt1
echo $copt # --opt1=/home/user1/work ; and nothing more

eval copt="${usr_opt[42]}"
gives an error
echo $copt # <nothing> # error: --opt2: command not found

Does the user quotes his string in the file then all is perfect:
options: "--opt1=$idir --opt2 --opt3="hello""
eval copt=${usr_opt[42]}
echo $copt # --opt1=/home/user1/work --opt2 --opt3="hello"

So is there an easier way as to check for the qotes in the string and if not quoted quote it?

BW-userx · 05-02-2017, 06:41 PM

check your format
http://tldp.org/LDP/abs/html/ivr.html

or try this

Code:

#!/bin/bash

for (( i = 0 ; i < 10 ; i++ ))
do

if [[ $(( $i % 2 )) -eq 0 ]] ;
then
 array[i]="no quotes"
else
 array[i]="\"quotes"\"

fi

done

for (( j = 0 ; j < ${#array[@]} ; j++ ))
{

  if [[ ! ${array[j]} =~ ^\".*\"$ ]]; then
    array[j]="\"${array[j]}"\"
  fi

}


for (( a = 0 ; a < ${#array[@]} ; a++ )) {
  echo "${array[a]}"
}
 echo "${array[@]}"

is this what you wanted?
Let me know if that works for you.

if no quotes on the ends of string in each element then adds quotes on the both ends of each string in each element.

ondoho · 05-03-2017, 02:13 AM

bastl, why are you using eval there?
is this a bash script?
from what i see, 'eval' is useless there and everything should work if you just remove all occurences of 'eval'.

pan64 · 05-03-2017, 02:19 AM

copt is an array, you should print it:

Code:

echo "${copt[@]}"
echo $copt # will print only the first element of the list

bastl · 05-03-2017, 01:40 PM

It's bash-4.x script!
echo does'n do the job you need eval or source.
But i have too many relations between these options that source isn't realy useful and is the reason of that option file.
So BW-userx your script looks very promising I'll test it and let you now here.
But you see how much lines you need only because the user could forget the quotes.
I hoped of something shorter like () or ...

BW-userx · 05-03-2017, 02:06 PM

Quote:

Originally Posted by bastl

It's bash-4.x script!
echo does'n do the job you need eval or source.
But i have too many relations between these options that source isn't realy useful and is the reason of that option file.
So BW-userx your script looks very promising I'll test it and let you now here.
But you see how much lines you need only because the user could forget the quotes.
I hoped of something shorter like () or ...

so become a programmer then you will gain an understanding the even the mv command has more then one line of code behind that one liner.

Code:

mv file file

In other words you could write a function that does what you want then call it a yeah 'a'

that short enough for you? Because that is how it works.

Code:

a()
{

for (( j = 0 ; j < ${#array[@]} ; j++ ))
{

  if [[ ! ${array[j]} =~ ^\".*\"$ ]]; then
    array[j]="\"${array[j]}"\"
  fi

}

}

a array[@]

Something like that.

bastl · 05-03-2017, 02:12 PM

O.K. BW-userx that works fine, many thanks:

Code:

if [[ ! ${usr_opt[42]} =~ ^\".*\"$ ]]
then
   eval copt="\"${usr_opt[42]}"\"
else
   eval copt="${usr_opt[42]}"
fi

BW-userx · 05-03-2017, 02:20 PM

Quote:

Originally Posted by bastl

O.K. BW-userx that works fine, many thanks:

Code:

if [[ ! ${usr_opt[42]} =~ ^\".*\"$ ]]
then
   eval copt="\"${usr_opt[42]}"\"
else
   eval copt="${usr_opt[42]}"
fi

you can shorten that you know.

think about what it is you are really checking for.

If not then make it so.
If yes then do nothing.

go back and look at my one line of code.

Code:

[[ ! ${usr_opt[42]} =~ ^\".*\"$ ]] &&  eval copt="\"${usr_opt[42]}"\"

What is 'eval' suppose to be doing for you?
Checking what you've already checked for?

bastl · 05-03-2017, 02:33 PM

Yes, and I'll shorten it one more, because not quoting is the standard in the option file. It was only for testing all possibilities and for learning.

BW-userx · 05-03-2017, 03:16 PM

keew, have fun.

pan64 · 05-04-2017, 12:28 AM

Code:

> usr_opt[42]='--opt1=$idir --opt2 --opt3="hello"'
> declare -a copt
> copt=( ${usr_opt[42]} )
> echo "${copt[0]}"
--opt1=$idir
> echo "${copt[1]}"
--opt2
> echo "${copt[2]}"
--opt3="hello"

I do not really understand why do you need to overcomplicate this?

BW-userx · 05-04-2017, 08:22 AM

Quote:

Originally Posted by pan64

Code:

> usr_opt[42]='--opt1=$idir --opt2 --opt3="hello"'
> declare -a copt
> copt=( ${usr_opt[42]} )
> echo "${copt[0]}"
--opt1=$idir
> echo "${copt[1]}"
--opt2
> echo "${copt[2]}"
--opt3="hello"

I do not really understand why do you need to overcomplicate this?

I know I am completely lost on this usage of eval when using it to check if something has quotes on both ends of a string. From what I read up on it. it is to run a command within it. I didn't piddle with it a lot. Not seeing a need for it. then you do this. it all looks Greek to me. And I do not wnat to over write this post. But I am putting in that link explaining this eval command.

http://www.softpanorama.org/Utilities/eval.shtml

pan64 · 05-04-2017, 09:18 AM

eval must not be used, it is unsafe and usually the situation can be solved (easily) without eval too.
There can be a few cases when eval is really required, but this is not the one.
The link you sent is more or less outdated, there are much better alternatives, just for example:

Code:

variable indirection:
abc=10 x=abc
echo ${!x}

last parameter in the list

Code:

set One Two Three Four
echo "${@:$#}"

what is a bit complicated the evaluation of string entered at the command prompt.
First bash will evaluate it, (it will also look for built-ins, functions, aliases) next it will pass the result to the command found and that command will also process the arguments. And you can protect the arguments using ' or ", but also you may need to pass " or any other strange chars as arguments.
The command eval will produce additional evaluation steps which will require additional protections which will definitely increase the complexity of argument passing (not to speak about remote ssh executions and other tricks, like pipe and redirection).

BW-userx · 05-04-2017, 09:41 AM

Quote:

Originally Posted by pan64

eval must not be used, it is unsafe and usually the situation can be solved (easily) without eval too.
There can be a few cases when eval is really required, but this is not the one.
The link you sent is more or less outdated,

That explains why when I googled eval I kept getting hits that the pages it sent me to where people were using everything but the eval command to do what was needed to be done.

Thanks for your input.

Laserbeak · 05-05-2017, 07:35 PM

What is readarray? What language are you using? You're only looking at your 6th and 42nd command-line option?

Looks like code gibberish to me!