grep
grep [0-9]
- print the lines that contain the numbers 0 through 9
grep -C 3 [pattern]
- print context of lines (specified number of lines above and below the pattern) for matching the pattern. Here, the number of lines is specified as 3
strings
strings is used to extract all character strings found in the file or files given as arguments. it is useful in locating human-readable content embedded in binary files; for text files one can just use grep
strings book1.xls | grep my_string
grep -e ^ts -e st$ /etc/services