Questions about: grep

grep is using regular expressions as defined by POSIX. For whatever reasons POSIX have not defined \t as tab. You have several alternatives: tell grep to use the regular expressions as defined by perl (perl has \t as tab): grep -P "\t" foo
About grepgrep syntaxgrep examplesRelated commandsLinux and Unix main page About grep grep, which stands for "global regular expression print," processes text line by line and prints any lines which match a specified pattern. grep syntax grep [OPTION