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Bad substitution - ShellCheck says okay

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# 1  
Old 02-02-2019
Bad substitution - ShellCheck says okay
ShellCheck doesn't find any issues with this script.
Code:
#!/bin/bash
# color_meanings: explain meanings of colors used in bash ls

eval "$(echo "no:fi:di:ln:pi:so:do:bd:cd:or:mi:su:sg:tw:st:ex" | sed -e 's/:/=/g; s/\;/\n/g')"
{
        IFS=:
        for i in $LS_COLORS
        do
                echo -e "\e[${i#*=}m$( x=${i%=*}; [ -n "${!x}" ] && echo "${!x}" || echo "$x" )\e[m"
        done
}

It prints out the colors and file descriptors, but then dozens of these messages follow:
Code:
/home/me/bin/color_meanings: line 9: *.tar: bad substitution
/home/me/bin/color_meanings: line 9: *.tgz: bad substitution
/home/me/bin/color_meanings: line 9: *.arc: bad substitution

# 2  
Old 02-02-2019
You haven't told us what shell and operating system you're using...

The command:
Code:
sed -e 's/:/=/g; s/\;/\n/g'

doesn't need the <backslash> before the <semicolon>. And, <backslash> before <n> is not portable. On some versions of sed that character pair will be translated to a <newline> character. On a sed that conforms to the standards, it produces unspecified results (frequently just the letter <n> on some systems). But since there aren't any <semicolon>s in the input being passed to sed I guess it doesn't really matter anyway???

Your script has no definition for LS_COLORS??? What are you hoping to have assigned to i on the various iterations through your loop?

And, of course, depending on what shell and OS you're using, the meaning of echo -e can vary widely.
# 3  
Old 02-02-2019
When I run
Code:
echo $LS_COLORS

on my system I get this result

Code:
rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.zst=01;31:*.tzst=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.wim=01;31:*.swm=01;31:*.dwm=01;31:*.esd=01;31:*.jpg=01;35:*.jpeg=01;35:*.mjpg=01;35:*.mjpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:

My guess is you get something similar. I believe the problem is the evaline of the script does not have a substitution string available for all the additional entries, such as *.tar=01;31
This User Gave Thanks to TioTony For This Post:
Xubuntu56
# 4  
Old 02-02-2019
Quote:
Originally Posted by TioTony
When I run
Code:
echo $LS_COLORS

on my system I get this result

Code:
rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.zst=01;31:*.tzst=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.wim=01;31:*.swm=01;31:*.dwm=01;31:*.esd=01;31:*.jpg=01;35:*.jpeg=01;35:*.mjpg=01;35:*.mjpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:

My guess is you get something similar. I believe the problem is the
Code:
eval

line of the script does not have a substitution string available for all the additional entries, such as
Code:
*.tar=01;31

Guess again. On my system, the command:
Code:
echo "$LS_COLORS"

produces a single, empty line of output. The variable LS_COLORS is not defined in my environment.

It looks to me like your eval command is evaluating a command that assigns a long string of characters to the variable named no. And, after doing that, nothing ever uses the variable named no. What are you trying to do with the eval command?

Why did you wrap the IFS=: and the for loop in braces? In the script you have shown us, removing that pair of braces would not affect the output produced by your script.
Last edited by Don Cragun; 02-02-2019 at 09:58 PM.. Reason: Fix typo: s/IFS=;/IFS=:/
# 5  
Old 02-02-2019
Sorry! Still new at this game.

Code:
Desktop: Xfce 4.12.3 (Gtk 2.24.31) Distro: Ubuntu 18.04.1 LTS
~$ echo $BASH_VERSION 4.4.19(1)-release

When I enter env, LS_COLORS is displayed with exactly what TioTony described.
I removed the two backslashes mentioned, but still got the same error messages.


EDIT: I removed the two braces, and got the same results as before.
Last edited by Xubuntu56; 02-02-2019 at 10:54 PM..
# 6  
Old 02-02-2019
Hi Xubuntu56,
What do you want the output of the command substitution:
Code:
$(echo "no:fi:di:ln:pi:so:do:bd:cd:or:mi:su:sg:tw:st:ex" | sed -e 's/:/=/g; s/\;/\n/g')

to be?

What are you hoping the eval command will do with the output of that command substitution?

What output are you hoping your script will produce?
# 7  
Old 02-02-2019
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.
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