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Diffstat (limited to 'doc/grep.texi')
| -rw-r--r-- | doc/grep.texi | 19 |
1 files changed, 15 insertions, 4 deletions
diff --git a/doc/grep.texi b/doc/grep.texi index b963108f..50a6938a 100644 --- a/doc/grep.texi +++ b/doc/grep.texi @@ -255,7 +255,7 @@ Print @var{num} lines of leading context before matching lines. Print @var{num} lines (default 2) of output context. -@item -NUM +@item -@var{num} @opindex -NUM Same as @samp{--context=@var{num}} lines of leading and trailing context. However, grep will never print any given line more than once. @@ -770,12 +770,14 @@ should avoid it. @node Usage @chapter Usage +@cindex Usage, examples Here is an example shell command that invokes @sc{gnu} @command{grep}: @example grep -i 'hello.*world' menu.h main.c @end example +@noindent This lists all lines in the files @file{menu.h} and @file{main.c} that contain the string @samp{hello} followed by the string @samp{world}; this is because @samp{.*} matches zero or more characters within a line. @@ -784,6 +786,8 @@ to ignore case, causing it to match the line @samp{Hello, world!}, which it would not otherwise match. @xref{Invoking}, for more details about how to invoke @command{grep}. +@cindex Using @command{grep}, Q&A +@cindex FAQ about @command{grep} usage Here are some common questions and answers about @command{grep} usage. @enumerate @@ -795,6 +799,7 @@ How can I list just the names of matching files? grep -l 'main' *.c @end example +@noindent lists the names of all C files in the current directory whose contents mention @samp{main}. @@ -805,14 +810,15 @@ How do I search directories recursively? grep -r 'hello' /home/gigi @end example +@noindent searches for @samp{hello} in all files under the directory @file{/home/gigi}. For more control of which files are searched, use @command{find}, @command{grep} and @command{xargs}. For example, the following command searches only C files: -@example +@smallexample find /home/gigi -name '*.c' -print | xargs grep 'hello' /dev/null -@end example +@end smallexample @item What if a pattern has a leading @samp{-}? @@ -821,6 +827,7 @@ What if a pattern has a leading @samp{-}? grep -e '--cut here--' * @end example +@noindent searches for all lines matching @samp{--cut here--}. Without @samp{-e}, @command{grep} would attempt to parse @samp{--cut here--} as a list of options. @@ -832,6 +839,7 @@ Suppose I want to search for a whole word, not a part of a word? grep -w 'hello' * @end example +@noindent searches only for instances of @samp{hello} that are entire words; it does not match @samp{Othello}. For more control, use @samp{\<} and @samp{\>} to match the start and end of words. For example: @@ -840,6 +848,7 @@ does not match @samp{Othello}. For more control, use @samp{\<} and grep 'hello\>' * @end example +@noindent searches only for words ending in @samp{hello}, so it matches the word @samp{Othello}. @@ -850,6 +859,7 @@ How do I output context around the matching lines? grep -C 2 'hello' * @end example +@noindent prints two lines of context around each matching line. @item @@ -897,10 +907,11 @@ I can do @sc{or} with @samp{|}, but what about @sc{and}? grep 'paul' /etc/motd | grep 'franc,ois' @end example +@noindent finds all lines that contain both @samp{paul} and @samp{franc,ois}. @item -How can I seach in both standard intput and in files? +How can I search in both standard input and in files? Use the special file name @samp{-}: |