The Programmer's Toolbox

• grep -- The grep command searches a list of files for a string. A typical use might be:

  grep mydefs.h *.c

  If you have ever forgotten to change a header file in one of your source files, and you don't know about grep, it's time to learn. There are heaps of options, so start by reading the man page.

• find -- find recursively searches the filesystem from a specified start point, matches files based on various criteria , and performs operations on the matched files. The simplest use is to "find" files (duh...):

  find . -name wander.c -print

  find /comp -name *.o -exec rm {}

  The first command searches from the current directory, matches files named wander.c and prints their locations. The second example searches everywhere below /comp for .o files, and deletes them. (Typed in at the command line, you would have to escape all the meta-characters.) As usual, there are a million options, so start by scanning the man page.

• xdiff and gdiff -- There is an old unix utility called diff that compares two files, and shows the difference between them (sort of). The only problem is that the language diff reports in is sed, which makes it a bit obtuse. Enter xdiff and gdiff, which do the same thing, except the report is a color coded, and graphically displayed. Much better for humans! There are differences between them, but mostly it boils down to whether you like GNU utilities or X11 utilities better.

  Example: Oops, lemma 3.1.4 is false. The following command helps you decide which end from which to start fixing it.

  xdiff paper.tex paper.tex~

• less -- less is a better more. In particular, it lets you backup in a document. Your first step is scan the man page and try it once. Your second step will then be to alias "more" to "less".

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Created: Fri Sep 8 11:39:00 1995 --- Last modified: Jun 18 1996