# Ad Hoc Data Analysis From The Unix Command Line/Picking The Data Apart With cut
## Fixed width data

How many households had just 1 person? Referring to the file layout, we see that the 106th and 107th characters of a household record indicate the number of people in the household. We can use the cut command to pull out just that bit of data from each record. The argument -c106-107 instructs cut to print the 106th through 107th characters of each line. The head command prints just the first few lines of a file (or its standard input).
You can give cut a comma separated list to pull out multiple ranges. To see the household id along with the number of occupants of the household:
The -c argument is used for working with so called "fixed-width" data. Data where the columns of a record are found at certain offset in bytes from the beginning of a record. Fixed width data abounds on a Unix system. ls -l writes its output in a fixed width format:
As does ps:
Returning to the question of how many 1 person households are there in Washington:
7,192, or about 28% of households have only one occupant.

## Delimited data

In delimited data, elements of a record are separated by a special 'delimiter' character. In the password file, fields are delimited by colons:
The 7th column of the password file is the user's login shell. How many people use bash as their shell?
You can give either -c or -f a comma separated list, so to see a few users that use tcsh as their shell:

### Tricky delimiters

The space character is a common delimiter. Unfortunately, your shell probably discards all extra whitespace on the command line. You can sneak a space character past your shell by wrapping it in quotes, like: cut -d" " -f 5
The tab character is another common delimiter. It can be hard to spot, because on the screen it just looks like any other white space. The od (octal dump) command can give you insight into the precise formatting of a file. For instance I have a file which maps first names to genders (with 95% probability). When casually inspected, it looks like fixed width data:
But on closer inspection there are tab characters delimiting the columns:
The first thing to do is read your system's manpage on "cut": it may already delimit by tab by default. If not, it requires a bit of trickery to get a tab character past your shell to the cut command. First, many shells have a feature called tab completion; when you hit tab they don't actually insert a tab, instead they attempt to figure out which file, directory or command you want and type that instead. In many shells you can overcome this special functionality by typing a control-v first. Whatever character you type after the control-v is literally inserted. Like a space character, you need to protect the tab character with quotes or the shell will discard it like any other white space separating pieces of the command line.
So to get the ratio of male first names to female first names I might run the following commands. Between the double quotes I typed control-v and then hit tab.
Apparently there's much more variation in female names than male names.
If your system's cut command delimits on tab, the above command becomes simply cut -f2 gender.txt.
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