Sorting and columns

Putting lines in order

sort arranges lines alphabetically (or, with -n, as numbers):

sort names.txt

sort -r reverses the order; sort -n is for lists of numbers.

Removing duplicates

uniq removes neighbouring repeated lines. Because it only looks at neighbours, you usually sort first:

sort names.txt | uniq

Add uniq -c to also count how many times each line appeared.

Picking out columns

Many files have columns separated by a character — a comma, a colon, a tab.
cut pulls out the columns you want. -d sets the delimiter, -f the field:

cut -d : -f 1 people.txt

That takes the first field of each name:age line — the names.

Get a tidy, de-duplicated list of names. Pipe sort into uniq: sort names.txt | uniq.

# sort the names, then remove duplicates

Click Run to see the output here.

people.txt has name:age on each line. Pull out just the names with cut -d : -f 1 people.txt.

# cut out the first field (the name), split on ":"

Click Run to see the output here.

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