Grep-q used for if logic judgment

Grep-q is used to determine if logic and suddenly finds that grep-q is useful for if logic judgment. -Q parameter, which is intended to be Quiet; donotwriteanythingtostandardoutput. Exitimmediatelywithzerostatusifanymatchis... grep-q is used to determine if logic and suddenly finds grep-q is used for if logic. -Q parameter, which is intended to be Quiet; do not write anything to standard output. exit immediately with zero status if any match is found, even if an error was detected. in quiet mode, no standard output is printed. If any matching content exists, the status value 0 is returned immediately. Application # cat a.txt nihao nihaooohello # if grep-q hello a.txt; then echo yes; else echo no; fi yes # if grep-q word a.txt; then echo yes; else echo no; fino