I have text files that include the ANSI movement codes ESC[xC and ESC[xD. I want to filter these out but with each line output with those codes taken into account.
Consider the line:
this cat is greenESC[12DdogESC[4Cwhite I would like this piped out as
this dog is white Above ESC means the escape code \0x1b (or \033).
I'm sure there's a better way (and I'm sure there's better Perl), but this seems to do the trick:
perl -M5';$e="\x1b";' -lne 'chomp;if(/$e\[\d+[CD]/){$ns="";$p=0;while(/$e\[(\d+)([CD])/g){if(!$ns){$ns=$`;$p=length($ns)}$p+=($2eq"C"?+$1:-$1);($a=$'"'"')=~s/(^[^$e]+).*/$1/;if($a=~/^[^$e]/){substr($ns,$p,length($a),$a);$p+=length($a)}}print $ns}else{print $_}' -l chomps already perl supports \e for ESC (inside "...", qq(...), /.../). $ string=$'this cat is green\e[12Ddog\e[4Cwhite' $ echo "$string" this dog is white Explanation: the $'...' syntax is ANSI-C Quoting, which expands the escape sequences in the string (you can also use \033—I just like \e better). This works in cases where the text stored in a variable already has the escape sequences interpreted.
$ string='this cat is green\e[12Ddog\e[4Cwhite' $ echo "${string@E}" this dog is white Explanation: the ${variable@E} syntax expands the backslash escape sequence in variable.
These first two methods work for me in bash 5.2.26, but if you have an older version, you may have to do it with printf:
$ string='this cat is green\033[12Ddog\033[4Cwhite' $ printf "%b\n" "$string" this dog is white Explanation: "%b" enables backslash interpretation for printf.
man ansi_codes, en.wikipedia.org/wiki/ANSI_escape_code ."\e\[[0-9;]*[A-Za-z]"is what I remember. But, if you're going to resolve 2 parameter cursor positioning commands, and^Hs, it's much harder