SPRING AND NEAP TIDES
the Earth–moon–sun geometry that makes the tides swing — after NOAA
CPR AND CHOKING
the 2025 American Heart Association algorithms, step by step — bystander, trained rescuer, and choking at three ages
HANDWASHING
five steps, and the 20 seconds that actually matter
FILE DESCRIPTORS
Three levels between a number and a file: what two numbers of one description share, what two descriptions do not — and where the offset lives
FILE LOCKS
A lock lies on a range of bytes, it has two different kinds of owner, and it guards no byte at all
FILE PERMISSIONS
Nine bits in three triads, three special bits — and why r and x on a directory are different powers
CSS FLEXBOX
main axis and cross axis · which property belongs to which
![FILENAME EXPANSION: *, ?, […]](/api/img/cmsp2eg3h001q2dpdnyxkt8mu)
FILENAME EXPANSION: *, ?, […]
A leading dot and a slash disappear only in filename expansion: the same pattern “*” is seen by case, but not by expansion itself
HERE-DOCUMENTS
The body reaches the command as a single word, and one quote in the delimiter decides whether it arrives as typed
IFS AND FIELD SPLITTING
Two kinds of delimiter: white ones merge into one, non-white ones each cut on their own — and the same value gives one field or four
${…}: FOUR MODIFICATIONS
The colon asks about emptiness too: in the column of the empty variable it changes the answer four times out of four, and in the other two columns none
read: A LINE INTO VARIABLES
The last variable takes the whole rest of the line, inner spaces and all; without -r the backslash disappears, and a line with no final newline gives status 1 — although the variable is already full
THE SELECT STATEMENT
8 clauses in the order you write them — and the order they take effect in
THE UMASK
The file mode creation mask: the nine bits it clears, five arguments that name opposite things — and why umask 022 is not chmod 755
WORD EXPANSION
Four steps in a fixed order — and only two of them can change how many fields reach the command
MATCHA DRINKS
six proportions · grams, millilitres, degrees
BABY-LED WEANING
cutting fruit and vegetables so a baby can feed itself: the shape, the size limit and what is never served
THE HAMBURGER
the ratios of the mince and the five steps that decide the result
THE CLOCK FACE
two hands, twelve numbers — how to read the time
MICROPHONE POSITIONS
where to place a mic around an acoustic guitar and how each spot sounds — after Shure’s guides
BARRE CHORDS
two shapes, twelve chords each
ARPEGGIOS ON TWO STRINGS
major and minor in one position · the bare triad, no octave
ARPEGGIOS ON THREE STRINGS
major and minor in one position · a whole octave on three strings
ARPEGGIOS ON FOUR STRINGS
major and minor in one position · exactly an octave, one note per string
ARPEGGIOS ON SIX STRINGS
major and minor in one position · two octaves from the root
FIRST CHORDS
15 chords every beginner starts with · standard tuning E A D G B e