Does the inverse command of cut exist?

Question

I like using the cut command in Linux with the -c flag. However, I'm interested in finding a command that sort of does the set inverse of cut. Essentially, given the input:

drwxrwxrwx 2 root root 4096 4096 4 20:15 bin
drwxrwxrwx 2 root root 4096 4096 4 20:15 Desktop

I would like to see everything except “4096 4 20:15”. Here is the output:

drwxrwxrwx 2 root root bin
drwxrwxrwx 2 root root Desktop

I want to be able to literally cut out between characters x and y, if that makes sense.

Any ideas? I can't imagine it'd be a hard script to write but if there already exists a command for it, I'd love to use it.

Answer 1

As others have pointed out, you should not parse the output of ls. Assuming you are using ls only as an example and will be parsing something else, there are a few ways of doing what you want:

1. cut with -d and -f

   cut -d ' ' -f 1,2,3,4,9
   

   from man cut:

   -d, --delimiter=DELIM
         use DELIM instead of TAB for field delimiter
   
   -f, --fields=LIST
         select only these fields;  also print any line
         that contains no delimiter  character,  unless
         the -s option is specified
   

   Specifically for ls this is likely to fail since ls will change the amount of whitespace between consecutive fields to make them align better. cut treats foo<space>bar and foo<space><space>bar differently.

2. awk and its variants split each input line into fields on white space so you can tell it to print only the fields you want:

   awk '{print $1,$2,$3,$4,$9}'
   

3. Perl

   perl -lane 'print "@F[0 .. 3,8]"'
   

Answer 2

You can get the inverse of the results of cut by using the --complement option. The cut man page says (somewhat unhelpfully):

--complement

          complement the set of selected bytes, characters or fields

So, for instance,

$ echo The fifth and sixth words will be missing | cut -d ' ' -f 5-6 --complement The fifth and sixth be missing

Explanation:

• -d ' ' sets the delimiter to the space character
• -f 5-6 selects the fields 5 through 6 ("words will") to be output
• --complement returns the complement (inverse) of the selected text

Answer 3

Using stat to replace ls isn't a drop-in replacement, so for all the well-intentioned admonishment against parsing ls, I can appreciate the seduction...

Here's an almost equivalent of of an ls -a in the current dir:

find . -maxdepth 1 -print0|xargs -0 stat --format="%A %U %G %n"

Here's the nearest I could get it:

find . -maxdepth 1 -print0\
|awk 'BEGIN{RS="\0";FS="/";ORS="\0"}{if(/\//){print $2}else{print}}'\
|xargs -0 stat --format="%A %U %G %n"\
|LC_COLLATE=C sort -k4 

Now, to take an argument instead of just ., you'd want to put it into a function kinda like this:

function ls4up() {
    find . -maxdepth 1 -print0\
    |awk 'BEGIN{RS="\0";FS="/";ORS="\0"}{if(/^[^\/][^\/]*\//){print $2}else{print}}'\
    |xargs -0 stat --format="%A %U %G %n"\
    |LC_COLLATE=C sort -k4 
}

So now you see how easy it is to use stat instead of trying to parse the output of ls or something. /s