@ -76,8 +76,9 @@ mirror</a>, and welcome feedback there.</p>
< li > < a href = "#code-help-code-and-man-pages" > < code > – help< / code > and man pages< / a > < / li >
< li > < a href = "#wc" > wc< / a > < / li >
< li > < a href = "#head-tail-and-cut" > head, tail, and cut< / a > < / li >
< li > < a href = "#tab-separated-values" > tab separated values< / a > < / li >
< li > < a href = "#finding-text-grep" > finding text: grep< / a > < / li >
< li > < a href = "#now-you-have-n-problems-regex-rabbit-holes" > now you have n problems: regex + rabbit holes< / a > < / li >
< li > < a href = "#now-you-have-n-problems-regex-and- rabbit-holes" > now you have n problems: regex and rabbit holes< / a > < / li >
< / ul >
< / li >
< li > < a href = "#a-literary-problem" > 2. a literary problem< / a > < / li >
@ -861,6 +862,190 @@ you could instead do:</p>
<!-- end -->
< h2 > < a name = tab-separated-values href = #tab-separated-values > #< / a > tab separated values< / h2 >
< p > Notice above how we had to tell < code > cut< / code > that “ fields” in < code > authors_*< / code > are
delimited by spaces? It turns out that if you don’ t use < code > -d< / code > , < code > cut< / code > defaults
to using tab characters for a delimiter.< / p >
< p > Tab characters are sort of weird little animals. You can’ t usually < em > see< / em > them
directly – they’ re like a space character that takes up more than one space
when displayed. By convention, one tab is usually rendered as 8 spaces, but
it’ s up to the software that’ s displaying the character what it wants to do.< / p >
< p > (In fact, it’ s more complicated than that: Tabs are often rendered as marking
< em > tab stops< / em > , which is a concept I remember from 7th grade typing classes, but
haven’ t actually thought about in my day-to-day life for nearly 20 years.)< / p >
< p > Here’ s a version of our < code > all_authors< / code > that’ s been rearranged so that the first
field is the author’ s last name, the second is their first name, the third is
their middle name or initial (if we know it) and the fourth is any suffix.
Fields are separated by a single tab character:< / p >
<!-- exec -->
< pre > < code > $ cat all_authors.tsv
Robinson Eden
Waring Gwendolyn L.
Tiptree James Jr.
Brunner John
Tolkien John Ronald Reuel
Walton Jo
Toews Miriam
Cadigan Pat
Le Guin Ursula K.
Veselka Vanessa
< / code > < / pre >
<!-- end -->
< p > That looks kind of garbled, right? In order to make it a little more obvious
what’ s happening, let’ s use < code > cat -T< / code > , which displays tab characters as < code > ^I< / code > :< / p >
<!-- exec -->
< pre > < code > $ cat -T all_authors.tsv
Robinson^IEden
Waring^IGwendolyn^IL.
Tiptree^IJames^I^IJr.
Brunner^IJohn
Tolkien^IJohn^IRonald Reuel
Walton^IJo
Toews^IMiriam
Cadigan^IPat
Le Guin^IUrsula^IK.
Veselka^IVanessa
< / code > < / pre >
<!-- end -->
< p > It looks odd when displayed because some names are at or nearly at 8 characters long.
“ Robinson” , at 8 characters, overshoots the first tab stop, so “ Eden” gets indented
further than other first names, and so on.< / p >
< p > Fortunately, in order to make this more human-readable, we can pass it through
< code > expand< / code > , which turns tabs into a given number of spaces (8 by default):< / p >
<!-- exec -->
< pre > < code > $ expand -t14 all_authors.tsv
Robinson Eden
Waring Gwendolyn L.
Tiptree James Jr.
Brunner John
Tolkien John Ronald Reuel
Walton Jo
Toews Miriam
Cadigan Pat
Le Guin Ursula K.
Veselka Vanessa
< / code > < / pre >
<!-- end -->
< p > Now it’ s easy to sort by last name:< / p >
<!-- exec -->
< pre > < code > $ sort -k1 all_authors.tsv | expand -t14
Brunner John
Cadigan Pat
Le Guin Ursula K.
Robinson Eden
Tiptree James Jr.
Toews Miriam
Tolkien John Ronald Reuel
Veselka Vanessa
Walton Jo
Waring Gwendolyn L.
< / code > < / pre >
<!-- end -->
< p > Or just extract middle names and initials:< / p >
<!-- exec -->
< pre > < code > $ cut -f3 all_authors.tsv | grep .
L.
Ronald Reuel
K.
< / code > < / pre >
<!-- end -->
< p > It probably won’ t surprise you to learn that there’ s a corresponding < code > paste< / code >
command, which takes two or more files and stitches them together with tab
characters. Let’ s extract a couple of things from our author list and put them
back together in a different order:< / p >
<!-- exec -->
< pre > < code > $ cut -f1 all_authors.tsv > lastnames
< / code > < / pre >
<!-- end -->
<!-- exec -->
< pre > < code > $ cut -f2 all_authors.tsv > firstnames
< / code > < / pre >
<!-- end -->
<!-- exec -->
< pre > < code > $ paste firstnames lastnames | sort -k2 | expand -t12
John Brunner
Pat Cadigan
Ursula Le Guin
Eden Robinson
James Tiptree
Miriam Toews
John Tolkien
Vanessa Veselka
Jo Walton
Gwendolyn Waring
< / code > < / pre >
<!-- end -->
< p > As these examples show, TSV is something very like a primitive spreadsheet: A
way to represent information in columns and rows. In fact, it’ s a close cousin
of CSV, which is often used as a lowest-common-denominator format for
transferring spreadsheets, and which represents data something like this:< / p >
< pre > < code > last,first,middle,suffix
Tolkien,John,Ronald Reuel,
Tiptree,James,,Jr.
< / code > < / pre >
< p > The advantage of tabs is that they’ re supported by a bunch of the standard
tools. A disadvantage is that they’ re kind of ugly and can be weird to deal
with, but they’ re useful anyway, and character-delimited rows are often a
good-enough way to hack your way through problems that call for basic
structure.< / p >
< h2 > < a name = finding-text-grep href = #finding-text-grep > #< / a > finding text: grep< / h2 >
< p > After all those contortions, what if you actually just want to see < em > which lists< / em >
@ -899,7 +1084,7 @@ words have been written on this topic by leading lights of the nerd community.</
isn’ t very useful to us). That’ s because all < code > grep< / code > saw was the lines in the
files, not the names of the files themselves.< / p >
< h2 > < a name = now-you-have-n-problems-regex-rabbit-holes href = #now-you-have-n-problems-regex-rabbit-holes > #< / a > now you have n problems: regex + rabbit holes< / h2 >
< h2 > < a name = now-you-have-n-problems-regex-and- rabbit-holes href = #now-you-have-n-problems-regex-and -rabbit-holes > #< / a > now you have n problems: regex and rabbit holes< / h2 >
< p > To close out this introductory chapter, let’ s spend a little time on a topic
that will likely vex, confound, and (occasionally) delight you for as long as
@ -936,18 +1121,18 @@ shell to match groups of files, but for text in general and with more magic.</p>
by < code > grep< / code > , other magical things include:< / p >
< table >
< tr > < td > < code > ^< / code > < / td > < td > start of a line < / td > < / tr >
< tr > < td > < code > $< / code > < / td > < td > end of a line < / td > < / tr >
< tr > < td > < code > [abc]< / code > < / td > < td > one of a, b, or c < / td > < / tr >
< tr > < td > < code > [a-z]< / code > < / td > < td > a character in the range a through z < / td > < / tr >
< tr > < td > < code > [0-9]< / code > < / td > < td > a character in the range 0 through 9 < / td > < / tr >
< tr > < td > < code > +< / code > < / td > < td > one or more of the preceding thing < / td > < / tr >
< tr > < td > < code > ?< / code > < / td > < td > 0 or 1 of the preceding thing < / td > < / tr >
< tr > < td > < code > *< / code > < / td > < td > any number of the preceding thing < / td > < / tr >
< tr > < td > < code > (foo|bar)< / code > < / td > < td > "foo" or "bar"< / td > < / tr >
< tr > < td > < code > (foo)?< / code > < / td > < td > optional "foo"< / td > < / tr >
< tr > < td > < code > ^< / code > < / td > < td > start of a line < / td > < / tr >
< tr > < td > < code > $< / code > < / td > < td > end of a line < / td > < / tr >
< tr > < td > < code > [abc]< / code > < / td > < td > one of a, b, or c < / td > < / tr >
< tr > < td > < code > [a-z]< / code > < / td > < td > a character in the range a through z< / td > < / tr >
< tr > < td > < code > [0-9]< / code > < / td > < td > a character in the range 0 through 9< / td > < / tr >
< tr > < td > < code > +< / code > < / td > < td > one or more of the preceding thing < / td > < / tr >
< tr > < td > < code > ?< / code > < / td > < td > 0 or 1 of the preceding thing < / td > < / tr >
< tr > < td > < code > *< / code > < / td > < td > any number of the preceding thing < / td > < / tr >
< tr > < td > < code > (foo|bar)< / code > < / td > < td > "foo" or "bar"< / td > < / tr >
< tr > < td > < code > (foo)?< / code > < / td > < td > optional "foo"< / td > < / tr >
< / table >
@ -1549,6 +1734,9 @@ the same thing as `cat all_authors | nl`, or `nl all_authors`. You won't see
$ sort colors | uniq -i | tail -1
$ cut -d' ' -f1 ./authors_* | sort | uniq -ci | sort -n | tail -3
$ sort -u ./authors_* | cut -d' ' -f1 | uniq -ci | sort -n | tail -3
$ sort -k1 all_authors.tsv | expand -t14
$ cut -f3 all_authors.tsv | grep .
$ paste firstnames lastnames | sort -k2 | expand -t12
$ cat ./authors_* | grep 'Vanessa'
< / code > < / pre >
@ -2447,11 +2635,9 @@ If you squint, these look kind of like paths to files on your filesystem.</p>
< hr / >
< script >
$(document).ready(function () {
// ☜ ☝ ☞ ☟
// ☆ ✠ ✡ ✢ ✣ ✤ ✥ ✦ ✧ ✩ ✪
var closed_sigil = '⇩';
var open_sigil = '⇧';
// ☜ ☝ ☞ ☟ ☆ ✠ ✡ ✢ ✣ ✤ ✥ ✦ ✧ ✩ ✪
var closed_sigil = 'show';
var open_sigil = 'hide';
var togglesigil = function (elem) {
var sigil = $(elem).html();
@ -2462,20 +2648,18 @@ $(document).ready(function () {
}
};
var togglebutton = function (e) {
e.preventDefault();
$details_full.toggle({
duration: 550
});
togglesigil(this);
};
$(".details").each(function () {
var $this = $(this);
var $button = $('< button class = clicker-button > ' + closed_sigil + '< / button > ');
var $details_full = $(this).find('.full');
$button.click(togglebutton);
$button.click(function (e) {
e.preventDefault();
$details_full.toggle({
duration: 550
});
togglesigil(this);
});
$(this).find('.clicker').append($button);
$button.show();
Brennen Bearnes
8 years ago