UNIX FILTERS

grep                           Search a file for a matching pattern or regular expression.

Usage: grep [options] <regular-expression> <file-name>

Options: -n print lines and line numbers

-v prints all the lines that do not contain the expression.

Eg: grep [a-z]*.C filename

grep *[SITE]* filename

fgrep                         A variation of grep that maches a text-string and does-not

support regular expressions.

Eg: fgrep <string> <file-name>

spell                          Exercise >> to be completed by students

sort                            Exercise >> to be completed by students

head                          Exercise >> to be completed by students

tail                             Exercise >> to be completed by students

find                            Search the system for filenames.

Usage: find <pathname> <condition>

Eg: find /home/hoda -name seed

split                           Splits a file into several files of equal length.

Usage: split [options] <filename> <outfile>.

Options: -n specifies the number of lines per file.

Another variation of split is csplit which splits the file using a specified expression as a splitting point.

cmp                           Compare 2 files.

Usage: cmp <file1> <file2>

diff                             Reports the lines that differ between 2 files

Usage: diff <file> <file2>

join                            A database operator that joins the common lines of two sorted  files.

Usage: join <file1> <file2>

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