Effective Vs. Real
Unix processes have an effective (EUID, EGID), a real (UID, GID) and a saved (SUID, SGID) ID. Normally these are identical, but in setgid processes they are different.
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Famous quotes containing the words effective and/or real:
“[Humanity] has unquestionably one really effective weapon—laughter. Power, money, persuasion, supplication, persecution—these can lift at a colossal humbug—push it a little—weaken it a little, century by century; but only laughter can blow it to rags and atoms at a blast. Against the assault of laughter nothing can stand.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)
“Although a firm swat could bring a recalcitrant child swiftly into line, the changes were usually external, lasting only as long as the swatter remained in view....Permanent transformation had to be internal....The habits of self discipline, as laborious and frustrating as they were to achieve, offered the only real possibility of keeping children safe from their own excesses as well as the omnipresent dangers of society.”
—Mary Kay Blakely (20th century)