How to use cut command to get the first and last elements of a row

cutkshtext processing

I've asked almost the same question already, but this time, I want to retrieve the X latest elements of a row of a CSV file. For example, with an input file as this one:

1;foo;bar;baz;x;y;z
2;foo;bar;baz;x;y;z
3;foo;bar;baz;x;y;z

What would be the command (eventually using cut) to get the last 2 columns, so I get:

y;z
y;z
y;z

In fact, my real target is to retrieve the first 3 and the last 2 fields of each row, so I get:

1;foo;bar;y;z
2;foo;bar;y;z
3;foo;bar;y;z

Unfortunately, I cannot use a command like cut -d \; -f 1-3,10-11 (if there are 11 elements in the row), because the CSV file does not respect the real CSV format. Indeed, some fields in the middle of the rows are encrypted, and their encrypted value may sometimes contains a ; characters (and of course, they are not wrapped inside "). In others words, my lines may look like that:

1;foo;bar;#@$"é&^l#;baz;x;y;z
2;foo;bar;#¤=é;)o'#;baz;x;y;z
3;foo;bar;#]]'~é{{#;baz;x;y;z

and as you can see, on the second line, there is an additional ; character, so I can't use here a command like cut -d \; -f 1-3,7-8, because if will return that, which is wrong:

1;foo;bar;y;z
2;foo;bar;x;y  (-> Wrong here, there is a shift)
3;foo;bar;y;z

So how can I use cut to solve my problem?

Thanks

ps: I am specially in love with the cut command, so if you have a command that does what I want but that is not cut, then it's fine too 🙂

Edit It seems important to note that the machine is quite old: uname -a give this message:

SunOS ###### 5.10 Generic_142900-05 sun4u sparc SUNW,Sun-Fire-V240

and some commands may not be present (like rev)

Best Answer

On your version of SunOS nawk(or for that matter awk) should be able to do the trick

 nawk -F';' 'BEGIN{OFS=";"}{print($1,$2,$3,$(NF-1),$(NF))}' file.txt

Related Solutions

Text Processing – Is There an Inverse Command of Cut?

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:

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.

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

Shell Script – Cut Tab-Delimited Text File Lines to 80 Characters

I think you're looking for expand and/or unexpand. It seems you're trying to ensure a \tab width counts as 8 chars rather than the single one. fold will do that as well, but it will wrap its input to the next line rather than truncating it. I think you want:

expand < input | cut -c -80

expand and unexpand are both POSIX specified:

The expand utility shall write files or the standard input to the standard output with \tab characters replaced with one or more space characters needed to pad to the next tab stop. Any backspace characters shall be copied to the output and cause the column position count for tab stop calculations to be decremented; the column position count shall not be decremented below zero.

Pretty simple. So, here's a look at what this does:

unset c i; set --;                                                             
until [ "$((i+=1))" -gt 10 ]; do set -- "$@" "$i" "$i"; done                      
for c in 'tr \\t \ ' expand;  do eval '                                           
    { printf "%*s\t" "$@"; echo; } | 
      tee /dev/fd/2 |'"$c"'| { 
      tee /dev/fd/3 | wc -c >&2; } 3>&1 |
      tee /dev/fd/2 | cut -c -80'
done

The until loop at top gets a set of data like...

1 1 2 2 3 3 ...

It printfs this with the %*s arg padding flag so for each of those in the set printf will pad with as many spaces as are in the number of the argument. To each one it appends a \tab character.

All of the tees are used to show the effects of each filter as it is applied.

And the effects are these:

1        2        3        4        5        6        7        8                9               10
1  2   3    4     5      6       7        8         9         10 
1  2   3    4     5      6       7        8         9         10 
66
1        2        3        4        5        6        7        8                9               10
1        2        3        4        5        6        7        8                9               10 
1        2        3        4        5        6        7        8                
105

Those rows are lined up in two sets like...

output of printf ...; echo
output of tr ... or expand
output of cut
output of wc

The top four rows are the results of the tr filter - in which each \tab is converted to a single space.

And the bottom four the results of the expand chain.

Best Answer

Related Solutions

Text Processing – Is There an Inverse Command of Cut?

Shell Script – Cut Tab-Delimited Text File Lines to 80 Characters

Related Question