egrep — Search a File for a Pattern, Using Full Regular Expressions
/usr/bin/egrep [-bchilnsv] [-e pattern-list] [-f file] [strings] [file...] /usr/xpg4/bin/egrep [-bchilnsvx] [-e pattern-list] [-f file] [strings] [file...]
The egrep (expression grep) command searches files for a pattern of characters and prints all lines that contain that pattern. egrep uses full regular expressions (expressions that have string values that use the full set of alphanumeric and special characters) to match the patterns. It uses a fast deterministic algorithm that sometimes needs exponential space.
If you specify no files, egrep assumes standard input. Normally, each line found is copied to the standard output. The file name is printed ...