Bad substitution - ShellCheck says okay


 
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# 8  
Old 02-02-2019
Quote:
Originally Posted by Xubuntu56
To answer the last question first, the script is producing the desired output: printing a legend for the different colors used by ls for each different type of file; i.e. di (directory) printed blue on a black background. I merely wanted it to do so without all the error messages.
So it is working, but with issues.
That is good to know, but please answer the other questions too. I'm not currently see any reason to keep the eval command in your script. If I knew why you had that line in your script, everything you're doing might suddenly make sense to me.
# 9  
Old 02-02-2019
I changed the script around a little bit. The "*." in many of the $LS_COLORS items is causing the problem. I couldn't figure out how to fix it in the for loop echo -e so I used sed to change the values before entering the loop. The 7 in 7z was also causing some issues, at least on my system. Here is the end result that I think does what you want:

Code:
#!/bin/bash
# color_meanings: explain meanings of colors used in bash ls

CLEAN_COLORS=`echo $LS_COLORS | sed -e 's/\*\.//g'`
{
        IFS=:
        for i in $CLEAN_COLORS
        do
		echo -e "\e[${i#*=}m$( x=${i%=*};echo "$x")\e[m"
        done
}

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# 10  
Old 02-03-2019
Assuming that you really want to see the *.'s in the output, but just don't want the diagnostics, see what happens if you try:
Code:
#!/bin/bash
OIFS=$IFS
IFS=':='
array=( $LS_COLORS )

IFS=$OIFS
printf '%s %s\n' "${array[@]}" | while read -r color sequence
do	printf '\e[%sm%s\e[m\n' "$sequence" "$color"
done

This User Gave Thanks to Don Cragun For This Post:
# 11  
Old 02-03-2019
Just switch off globbing temporarily ? In the OP's example:
Code:
        IFS=:
        set -f
        for i in $LS_COLORS
        do
                echo -e "\e[${i#*=}m$( x=${i%=*}; [ -n "${!x}" ] && echo "${!x}" || echo "$x" )\e[m"
        done
        set +f

--
shellcheck will check syntax, but it cannot know what is in the variables.

Last edited by Scrutinizer; 02-03-2019 at 03:58 AM..
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# 12  
Old 02-03-2019
The problem in your approach in post #1 is bash's "indirection". man bash:
Quote:
Parameter Expansion
.
.
.
If the first character of parameter is an exclamation point (!), and parameter is not a nameref, it introduces a level of variable indirection.
That indirection works (in fact supplies an empty string) if x holds a string that could be a valid variable name but fails on * or . (which can't be part of a valid variable name).
@Scrutinizer: that's why the -f option doesn't take effect - no pathname expansion attempted.



May I question the use of indirection in your script? What do you want to achieve by using it? Your simplified script, purged from indirection, looks like
Code:
IFS=':'
for i in $LS_COLORS
   do   echo -e "\e[${i#*=}m${i%=*}\e[m"
   done
[[0mrs[[m
[[01;34mdi[[m
[[01;36mln[[m
[[00mmh[[m
[[40;33mpi[[m
[[01;35mso[[m
[[01;35mdo[[m
[[40;33;01mbd[[m
[[40;33;01mcd[[m
[[40;31;01mor[[m
[[00mmi[[m
[[37;41msu[[m
[[30;43msg[[m
[[30;41mca[[m
[[30;42mtw[[m
[[34;42mow[[m
[[37;44mst[[m
[[01;32mex[[m
[[01;31m*.tar[[m
[[01;31m*.tgz[[m
 [[01;31m*.arc[[m

and works perfectly well. I showed the console codes as the colours don't translate to html too well.


EDIT: Added the IFS defnition to enable the script's success...

Last edited by RudiC; 02-03-2019 at 06:14 PM..
This User Gave Thanks to RudiC For This Post:
# 13  
Old 02-03-2019
@Don Cragun: good approach, but I had to modify it slightly to make it run on my linux host, like:


Code:
printf '%s\n' "${array[@]}" | while IFS== read -r color sequence
  do    printf '\e[%sm%s\e[m\n' "$sequence" "$color"
   done

(print just one array element at a time, and split the line read at the = sign.)




EDIT: I have to apologize; my fault when creating array. Don Cragun's code works flawlessly if array is defined the way he did in his post, with an element pair per colour entry.

Last edited by RudiC; 02-03-2019 at 06:07 PM..
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# 14  
Old 02-03-2019
Hi Xubuntu56...



Quote:
ShellCheck doesn't find any issues with this script.
REMEMBER!
ShellCheck ONLY checks validity and syntax of the shell in use, and NOT ALL shells.
For that is is simply superb. However don't expect it to check validity and syntax of transient commands.

A deliberate simple example from ShellCheck.


As you can see, 'sed' and 'sleep' will create an error and has absolutely no idea what 'junk_command' is.
Hope this helps.
Bad substitution - ShellCheck says okay-shellcheckpng
This User Gave Thanks to wisecracker For This Post:
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