Shortcuts in Science: November 2016

Monday, 14 November 2016

Thursday, 10 November 2016

S-adenosyl-L-methionine (SAMe)

Cited from SAMe Safety

"SAMe is likely safe when taken by mouth in doses of 400-600 milligrams daily for up to two years; when taken by mouth at doses of 800-1,600 milligrams daily for up to 42 days; and when given through IV in doses up to 800 milligrams daily for up to 21 days."

Read Command

Cited from Getting User Input Via Keyboard

While Read Loop

Cited from For and Read-While Loops in Bash

while read line

echo "$line"

done < list-of-dirs.txt

while read line

echo "$line"

done < <(cat list-of-dirs.txt)

Cited from While loop

while IFS= read -r line

command1 on $line

command2 on $line

....

commandN

done < "/path/to/filename"

or

while IFS= read -r field1 filed2 field3 ... fieldN

command1 on $field1

command2 on $field1 and $field3

....

commandN on $field1 ... $fieldN

done < "/path/to dir/file name with space"

"IFS is used to set field separator (default is while space). The -r option to read command disables backslash escaping (e.g., \n, \t). This is failsafe while read loop for reading text files."

Differences Between $@ and $* as Positional Parameters

Cited from $IFS

$@ expanded as "$1" "$2" "$3" ... "$n"
$* expanded as "$1y$2y$3y...$n", where y is the value of IFS variable i.e. "$*" is one long string and $IFS act as an separator or token delimiters.

IFS

Cited from Bash: Show IFS value

To show IFS value,
printf %q "$IFS"

What is the meaning of IFS=$'\n' in bash scripting?

Cited from Getting User Input Via Keyboard

cat -etv <<<"$IFS"

Sample outputs:
^I$

Where,

$ - end of line i.e. newline
^I$ - tab and newline

Arguments for "Format"

Cited from The printf command

%f Interpret and print the associated argument as floating point number
%e Interpret the associated argument as double, and print it in <N>±e<N> format
%g Interprets the associated argument as double, but prints it like %f or %e

Shortcuts in Science