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Old 05-30-2011, 09:08 PM
Dotan Cohen
 
Default Grep: show me this line and the next N lines?

Can grep show the matching lines and the next N lines after a match?
For instance, I have a config file wit hthe following text:
[Tag h1]
foreground=#2e5a03
underline=double
indent=0
weight=PANGO_WEIGHT_BOLD
scale=2.25

I would ideally grep on "[Tag h1]" and have grep display the match and
the next 5 lines so that I see all the content of the h1 section.

Can this be done?

Thanks!

--
Dotan Cohen

http://gibberish.co.il
http://what-is-what.com
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Old 05-30-2011, 09:13 PM
Pintr Tibor
 
Default Grep: show me this line and the next N lines?

On 05/30/2011 11:08 PM, Dotan Cohen wrote:
> Can grep show the matching lines and the next N lines after a match?
> For instance, I have a config file wit hthe following text:
> [Tag h1]
> foreground=#2e5a03
> underline=double
> indent=0
> weight=PANGO_WEIGHT_BOLD
> scale=2.25
>
> I would ideally grep on "[Tag h1]" and have grep display the match and
> the next 5 lines so that I see all the content of the h1 section.
>
> Can this be done?
>
> Thanks!
>

man grep

hint: A

t
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Old 05-30-2011, 09:14 PM
Ljubomir Ljubojevic
 
Default Grep: show me this line and the next N lines?

Dotan Cohen wrote:
> Can grep show the matching lines and the next N lines after a match?
> For instance, I have a config file wit hthe following text:
> [Tag h1]
> foreground=#2e5a03
> underline=double
> indent=0
> weight=PANGO_WEIGHT_BOLD
> scale=2.25
>
> I would ideally grep on "[Tag h1]" and have grep display the match and
> the next 5 lines so that I see all the content of the h1 section.
>
> Can this be done?
>
> Thanks!
>
man grep says "-A 5" would give you matching line + 5 more.

Ljubomir
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Old 05-30-2011, 09:15 PM
Meenoo Shivdasani
 
Default Grep: show me this line and the next N lines?

On Mon, May 30, 2011 at 5:08 PM, Dotan Cohen <dotancohen@gmail.com> wrote:


Can grep show the matching lines and the next N lines after a match?
*
I would ideally grep on "[Tag h1]" and have grep display the match and

the next 5 lines so that I see all the content of the h1 section.

Try*
grep -A 5 pattern filename*
M
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Old 05-30-2011, 09:15 PM
"John R. Dennison"
 
Default Grep: show me this line and the next N lines?

On Tue, May 31, 2011 at 12:08:37AM +0300, Dotan Cohen wrote:
>
> Can this be done?

"man grep" - I think you will be surprised when you take a look at it.




John
--
Worrying works. About 90% of the things I worry about never happen.

-- Woody Paige (1946-), sports columnist, on ESPN's "Around the Horn"
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Old 05-30-2011, 10:10 PM
Dotan Cohen
 
Default Grep: show me this line and the next N lines?

Thanks, all. I did actually look at the grep manpage but after a few
screenfuls it became tl;dr and I started just skimming. I suppose that
I skimmed too fast!

Thanks!

--
Dotan Cohen

http://gibberish.co.il
http://what-is-what.com
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Old 05-30-2011, 10:26 PM
"John R. Dennison"
 
Default Grep: show me this line and the next N lines?

On Tue, May 31, 2011 at 01:10:40AM +0300, Dotan Cohen wrote:
> Thanks, all. I did actually look at the grep manpage but after a few
> screenfuls it became tl;dr and I started just skimming. I suppose that
> I skimmed too fast!

Um....

It's the first option described.




John
--
Mankind is a single body and each nation a part of that body. We must
never say "What does it matter to me if some part of the world is ailing?"
If there is such an illness, we must concern ourselves with it as though we
were having that illness.

Mustafa Kemal Ataturk (1881-1938), founder and first President of the
Republic of Turkey
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Old 05-31-2011, 07:43 AM
Dotan Cohen
 
Default Grep: show me this line and the next N lines?

On Tue, May 31, 2011 at 01:26, John R. Dennison <jrd@gerdesas.com> wrote:
> On Tue, May 31, 2011 at 01:10:40AM +0300, Dotan Cohen wrote:
>> Thanks, all. I did actually look at the grep manpage but after a few
>> screenfuls it became tl;dr and I started just skimming. I suppose that
>> I skimmed too fast!
>
> Um....
>
> It's the first option described.
>

I see now that the server's grep manpage (CentOS) does in fact put it
right there at the top. I usually pull up manpages on localhost, not
what I'm SSHing into, and on this Debian-Derived distro it is buried
halfway down the third page of nine. That is interesting, and I'm sure
that there is a lesson to be learned from that!

GREP(1)

GREP(1)



NAME
grep, egrep, fgrep, rgrep - print lines matching a pattern

SYNOPSIS
grep [OPTIONS] PATTERN [FILE...]
grep [OPTIONS] [-e PATTERN | -f FILE] [FILE...]

DESCRIPTION
grep searches the named input FILEs (or standard input if
no files are named, or if a single hyphen-minus (-) is given as file
name) for lines
containing a match to the given PATTERN. By default, grep
prints the matching lines.

In addition, three variant programs egrep, fgrep and rgrep are
available. egrep is the same as grep -E. fgrep is the same as grep
-F. rgrep is
the same as grep -r. Direct invocation as either egrep or
fgrep is deprecated, but is provided to allow historical applications
that rely on them
to run unmodified.

OPTIONS
Generic Program Information
--help Print a usage message briefly summarizing these
command-line options and the bug-reporting address, then exit.

-V, --version
Print the version number of grep to the standard output
stream. This version number should be included in all bug reports
(see below).

Matcher Selection
-E, --extended-regexp
Interpret PATTERN as an extended regular expression
(ERE, see below). (-E is specified by POSIX.)

-F, --fixed-strings
Interpret PATTERN as a list of fixed strings, separated
by newlines, any of which is to be matched. (-F is specified by
POSIX.)

-G, --basic-regexp
Interpret PATTERN as a basic regular expression (BRE,
see below). This is the default.

-P, --perl-regexp
Interpret PATTERN as a Perl regular expression. This is
highly experimental and grep -P may warn of unimplemented features.

Matching Control
-e PATTERN, --regexp=PATTERN
Use PATTERN as the pattern. This can be used to specify
multiple search patterns, or to protect a pattern beginning with a
hyphen (-). (-e
is specified by POSIX.)

-f FILE, --file=FILE
Obtain patterns from FILE, one per line. The empty file
contains zero patterns, and therefore matches nothing. (-f is
specified by POSIX.)

-i, --ignore-case
Ignore case distinctions in both the PATTERN and the
input files. (-i is specified by POSIX.)

-v, --invert-match
Invert the sense of matching, to select non-matching
lines. (-v is specified by POSIX.)

-w, --word-regexp
Select only those lines containing matches that form
whole words. The test is that the matching substring must either be
at the beginning of
the line, or preceded by a non-word constituent
character. Similarly, it must be either at the end of the line or
followed by a non-word
constituent character. Word-constituent characters are
letters, digits, and the underscore.

-x, --line-regexp
Select only those matches that exactly match the whole
line. (-x is specified by POSIX.)

-y Obsolete synonym for -i.

General Output Control
-c, --count
Suppress normal output; instead print a count of
matching lines for each input file. With the -v, --invert-match
option (see below), count
non-matching lines. (-c is specified by POSIX.)

--color[=WHEN], --colour[=WHEN]
Surround the matched (non-empty) strings, matching
lines, context lines, file names, line numbers, byte offsets, and
separators (for fields
and groups of context lines) with escape sequences
to display them in color on the terminal. The colors are defined by
the environment
variable GREP_COLORS. The deprecated environment
variable GREP_COLOR is still supported, but its setting does not have
priority. WHEN is
never, always, or auto.

-L, --files-without-match
Suppress normal output; instead print the name of each
input file from which no output would normally have been printed. The
scanning will
stop on the first match.

-l, --files-with-matches
Suppress normal output; instead print the name of each
input file from which output would normally have been printed. The
scanning will stop
on the first match. (-l is specified by POSIX.)

-m NUM, --max-count=NUM
Stop reading a file after NUM matching lines. If the
input is standard input from a regular file, and NUM matching lines
are output, grep
ensures that the standard input is positioned to just
after the last matching line before exiting, regardless of the
presence of trailing
context lines. This enables a calling process to resume
a search. When grep stops after NUM matching lines, it outputs any
trailing context
lines. When the -c or --count option is also used, grep
does not output a count greater than NUM. When the -v or
--invert-match option is
also used, grep stops after outputting NUM non-matching lines.

-o, --only-matching
Print only the matched (non-empty) parts of a matching
line, with each such part on a separate output line.

-q, --quiet, --silent
Quiet; do not write anything to standard output.
Exit immediately with zero status if any match is found, even if an
error was detected.
Also see the -s or --no-messages option. (-q is
specified by POSIX.)

-s, --no-messages
Suppress error messages about nonexistent or unreadable
files. Portability note: unlike GNU grep, 7th Edition Unix grep did
not conform to
POSIX, because it lacked -q and its -s option
behaved like GNU grep's -q option. USG-style grep also lacked -q but
its -s option behaved
like GNU grep. Portable shell scripts should avoid both
-q and -s and should redirect standard and error output to /dev/null
instead. (-s
is specified by POSIX.)

Output Line Prefix Control
-b, --byte-offset
Print the 0-based byte offset within the input file
before each line of output. If -o (--only-matching) is specified,
print the offset of
the matching part itself.

-H, --with-filename
Print the file name for each match. This is the default
when there is more than one file to search.

-h, --no-filename
Suppress the prefixing of file names on output. This is
the default when there is only one file (or only standard input) to
search.

--label=LABEL
Display input actually coming from standard input as
input coming from file LABEL. This is especially useful when
implementing tools like
zgrep, e.g., gzip -cd foo.gz | grep --label=foo -H
something. See also the -H option.

-n, --line-number
Prefix each line of output with the 1-based line number
within its input file. (-n is specified by POSIX.)

-T, --initial-tab
Make sure that the first character of actual line
content lies on a tab stop, so that the alignment of tabs looks
normal. This is useful
with options that prefix their output to the actual
content: -H,-n, and -b. In order to improve the probability that
lines from a single
file will all start at the same column, this also
causes the line number and byte offset (if present) to be printed in a
minimum size field
width.

-u, --unix-byte-offsets
Report Unix-style byte offsets. This switch causes grep
to report byte offsets as if the file were a Unix-style text file,
i.e., with CR
characters stripped off. This will produce results
identical to running grep on a Unix machine. This option has no
effect unless -b option
is also used; it has no effect on platforms other than
MS-DOS and MS-Windows.

-Z, --null
Output a zero byte (the ASCII NUL character) instead of
the character that normally follows a file name. For example, grep
-lZ outputs a
zero byte after each file name instead of the usual
newline. This option makes the output unambiguous, even in the
presence of file names
containing unusual characters like newlines. This
option can be used with commands like find -print0, perl -0, sort -z,
and xargs -0 to
process arbitrary file names, even those that contain
newline characters.

Context Line Control
-A NUM, --after-context=NUM
Print NUM lines of trailing context after matching
lines. Places a line containing a group separator (--) between
contiguous groups of
matches. With the -o or --only-matching option, this
has no effect and a warning is given.

-B NUM, --before-context=NUM
Print NUM lines of leading context before matching
lines. Places a line containing a group separator (--) between
contiguous groups of
matches. With the -o or --only-matching option, this
has no effect and a warning is given.

-C NUM, -NUM, --context=NUM
Print NUM lines of output context. Places a line
containing a group separator (--) between contiguous groups of
matches. With the -o or
--only-matching option, this has no effect and a warning is given.

File and Directory Selection
-a, --text
Process a binary file as if it were text; this is
equivalent to the --binary-files=text option.

--binary-files=TYPE
If the first few bytes of a file indicate that the file
contains binary data, assume that the file is of type TYPE. By
default, TYPE is
binary, and grep normally outputs either a one-line
message saying that a binary file matches, or no message if there is
no match. If TYPE
is without-match, grep assumes that a binary file does
not match; this is equivalent to the -I option. If TYPE is text,
grep processes a
binary file as if it were text; this is equivalent to
the -a option. Warning: grep --binary-files=text might output binary
garbage, which
can have nasty side effects if the output is a terminal
and if the terminal driver interprets some of it as commands.

-D ACTION, --devices=ACTION
If an input file is a device, FIFO or socket, use ACTION
to process it. By default, ACTION is read, which means that devices
are read just
as if they were ordinary files. If ACTION is skip,
devices are silently skipped.

-d ACTION, --directories=ACTION
If an input file is a directory, use ACTION to process
it. By default, ACTION is read, which means that directories are read
just as if they
were ordinary files. If ACTION is skip, directories are
silently skipped. If ACTION is recurse, grep reads all files under
each directory,
recursively; this is equivalent to the -r option.

--exclude=GLOB
Skip files whose base name matches GLOB (using wildcard
matching). A file-name glob can use *, ?, and [...] as wildcards,
and to quote a
wildcard or backslash character literally.

--exclude-from=FILE
Skip files whose base name matches any of the file-name
globs read from FILE (using wildcard matching as described under
--exclude).

--exclude-dir=DIR
Exclude directories matching the pattern DIR from
recursive searches.

-I Process a binary file as if it did not contain matching
data; this is equivalent to the --binary-files=without-match option.

--include=GLOB
Search only files whose base name matches GLOB (using
wildcard matching as described under --exclude).

-R, -r, --recursive
Read all files under each directory, recursively; this
is equivalent to the -d recurse option.

Other Options
--line-buffered
Use line buffering on output. This can cause a
performance penalty.

--mmap If possible, use the mmap(2) system call to read input,
instead of the default read(2) system call. In some situations,
--mmap yields better
performance. However, --mmap can cause undefined
behavior (including core dumps) if an input file shrinks while grep is
operating, or if an
I/O error occurs.

-U, --binary
Treat the file(s) as binary. By default, under MS-DOS
and MS-Windows, grep guesses the file type by looking at the contents
of the first
32KB read from the file. If grep decides the file
is a text file, it strips the CR characters from the original file
contents (to make
regular expressions with ^ and $ work correctly).
Specifying -U overrules this guesswork, causing all files to be read
and passed to the
matching mechanism verbatim; if the file is a text file
with CR/LF pairs at the end of each line, this will cause some regular
expressions to
fail. This option has no effect on platforms other than
MS-DOS and MS-Windows.

-z, --null-data
Treat the input as a set of lines, each terminated by a
zero byte (the ASCII NUL character) instead of a newline. Like the
-Z or --null
option, this option can be used with commands like sort
-z to process arbitrary file names.

REGULAR EXPRESSIONS
A regular expression is a pattern that describes a set of
strings. Regular expressions are constructed analogously to
arithmetic expressions, by
using various operators to combine smaller expressions.

grep understands three different versions of regular expression
syntax: “basic,” “extended” and “perl.” In GNU grep, there is no
difference in
available functionality between basic and extended syntaxes.
In other implementations, basic regular expressions are less powerful.
The following
description applies to extended regular expressions;
differences for basic regular expressions are summarized afterwards.
Perl regular expressions
give additional functionality, and are documented in
pcresyntax(3) and pcrepattern(3), but may not be available on every
system.

The fundamental building blocks are the regular expressions
that match a single character. Most characters, including all letters
and digits, are
regular expressions that match themselves. Any meta-character
with special meaning may be quoted by preceding it with a backslash.

The period . matches any single character.

Character Classes and Bracket Expressions
A bracket expression is a list of characters enclosed by [ and
]. It matches any single character in that list; if the first
character of the list
is the caret ^ then it matches any character not in the list.
For example, the regular expression [0123456789] matches any single
digit.

Within a bracket expression, a range expression consists
of two characters separated by a hyphen. It matches any single
character that sorts
between the two characters, inclusive, using the locale's
collating sequence and character set. For example, in the default C
locale, [a-d] is
equivalent to [abcd]. Many locales sort characters in
dictionary order, and in these locales [a-d] is typically not
equivalent to [abcd]; it might
be equivalent to [aBbCcDd], for example. To obtain the
traditional interpretation of bracket expressions, you can use the C
locale by setting the
LC_ALL environment variable to the value C.

Finally, certain named classes of characters are predefined
within bracket expressions, as follows. Their names are self
explanatory, and they are
[:alnum:], [:alpha:], [:cntrl:], [:digit:], [:graph:],
[:lower:], [rint:], [unct:], [:space:], [:upper:], and
[:xdigit:]. For example,
[[:alnum:]] means [0-9A-Za-z], except the latter form depends
upon the C locale and the ASCII character encoding, whereas the former
is independent
of locale and character set. (Note that the brackets in these
class names are part of the symbolic names, and must be included in
addition to the
brackets delimiting the bracket expression.) Most
meta-characters lose their special meaning inside bracket expressions.
To include a literal ]
place it first in the list. Similarly, to include a literal ^
place it anywhere but first. Finally, to include a literal - place it
last.

Anchoring
The caret ^ and the dollar sign $ are meta-characters that
respectively match the empty string at the beginning and end of a
line.

The Backslash Character and Special Expressions
The symbols < and > respectively match the empty string at
the beginning and end of a word. The symbol  matches the empty
string at the edge of
a word, and B matches the empty string provided it's not at
the edge of a word. The symbol w is a synonym for [[:alnum:]] and W
is a synonym for
[^[:alnum:]].

Repetition
A regular expression may be followed by one of several
repetition operators:
? The preceding item is optional and matched at most once.
* The preceding item will be matched zero or more times.
+ The preceding item will be matched one or more times.
{n} The preceding item is matched exactly n times.
{n,} The preceding item is matched n or more times.
{,m} The preceding item is matched at most m times.
{n,m} The preceding item is matched at least n times, but not
more than m times.

Concatenation
Two regular expressions may be concatenated; the resulting
regular expression matches any string formed by concatenating
two substrings that
respectively match the concatenated expressions.

Alternation
Two regular expressions may be joined by the infix
operator |; the resulting regular expression matches any string
matching either alternate
expression.

Precedence
Repetition takes precedence over concatenation, which in turn
takes precedence over alternation. A whole expression may be enclosed
in parentheses
to override these precedence rules and form a subexpression.

Back References and Subexpressions
The back-reference
, where n is a single digit, matches
the substring previously matched by the nth parenthesized
subexpression of the regular
expression.

Basic vs Extended Regular Expressions
In basic regular expressions the meta-characters ?, +, {, |, (,
and ) lose their special meaning; instead use the backslashed versions
?, +, {,
|, (, and ).

Traditional egrep did not support the { meta-character, and
some egrep implementations support { instead, so portable scripts
should avoid { in
grep -E patterns and should use [{] to match a literal {.

GNU grep -E attempts to support traditional usage by assuming
that { is not special if it would be the start of an invalid interval
specification.
For example, the command grep -E '{1' searches for the
two-character string {1 instead of reporting a syntax error in the
regular expression.
POSIX.2 allows this behavior as an extension, but portable
scripts should avoid it.

ENVIRONMENT VARIABLES
The behavior of grep is affected by the following environment variables.

The locale for category LC_foo is specified by examining the
three environment variables LC_ALL, LC_foo, LANG, in that order. The
first of these
variables that is set specifies the locale. For example,
if LC_ALL is not set, but LC_MESSAGES is set to pt_BR, then the
Brazilian Portuguese
locale is used for the LC_MESSAGES category. The C locale is
used if none of these environment variables are set, if the locale
catalog is not
installed, or if grep was not compiled with national language
support (NLS).

GREP_OPTIONS
This variable specifies default options to be
placed in front of any explicit options. For example, if
GREP_OPTIONS is '--binary-
files=without-match --directories=skip', grep behaves as
if the two options --binary-files=without-match and
--directories=skip had been
specified before any explicit options. Option
specifications are separated by whitespace. A backslash escapes the
next character, so it can
be used to specify an option containing whitespace or a backslash.

GREP_COLOR
This variable specifies the color used to highlight
matched (non-empty) text. It is deprecated in favor of GREP_COLORS,
but still supported.
The mt, ms, and mc capabilities of GREP_COLORS have
priority over it. It can only specify the color used to highlight the
matching non-empty
text in any matching line (a selected line when the -v
command-line option is omitted, or a context line when -v is
specified). The default
is 01;31, which means a bold red foreground text on the
terminal's default background.

GREP_COLORS
Specifies the colors and other attributes used to
highlight various parts of the output. Its value is a colon-separated
list of capabilities
that defaults to
ms=01;31:mc=01;31:sl=:cx=:fn=35:ln=32:bn=32:se=36 with the rv and ne
boolean capabilities omitted (i.e., false). Supported
capabilities are as follows.

sl= SGR substring for whole selected lines (i.e.,
matching lines when the -v command-line option is omitted, or
non-matching lines when -v
is specified). If however the boolean rv
capability and the -v command-line option are both specified, it
applies to context matching
lines instead. The default is empty (i.e., the
terminal's default color pair).

cx= SGR substring for whole context lines (i.e.,
non-matching lines when the -v command-line option is omitted, or
matching lines when -v
is specified). If however the boolean rv
capability and the -v command-line option are both specified, it
applies to selected non-
matching lines instead. The default is empty
(i.e., the terminal's default color pair).

rv Boolean value that reverses (swaps) the
meanings of the sl= and cx= capabilities when the -v command-line
option is specified. The
default is false (i.e., the capability is omitted).

mt=01;31
SGR substring for matching non-empty text in any
matching line (i.e., a selected line when the -v command-line option
is omitted, or a
context line when -v is specified). Setting this
is equivalent to setting both ms= and mc= at once to the same value.
The default is
a bold red text foreground over the current line
background.

ms=01;31
SGR substring for matching non-empty text in a
selected line. (This is only used when the -v command-line option is
omitted.) The
effect of the sl= (or cx= if rv) capability
remains active when this kicks in. The default is a bold red text
foreground over the
current line background.

mc=01;31
SGR substring for matching non-empty text in a
context line. (This is only used when the -v command-line option is
specified.) The
effect of the cx= (or sl= if rv) capability
remains active when this kicks in. The default is a bold red text
foreground over the
current line background.

fn=35 SGR substring for file names prefixing any
content line. The default is a magenta text foreground over the
terminal's default
background.

ln=32 SGR substring for line numbers prefixing
any content line. The default is a green text foreground over the
terminal's default
background.

bn=32 SGR substring for byte offsets prefixing any
content line. The default is a green text foreground over the
terminal's default
background.

se=36 SGR substring for separators that are inserted
between selected line fields (, between context line fields, (-),
and between groups
of adjacent lines when nonzero context is
specified (--). The default is a cyan text foreground over
the terminal's default
background.

ne Boolean value that prevents clearing to the
end of line using Erase in Line (EL) to Right (33[K) each time a
colorized item ends.
This is needed on terminals on which EL is not
supported. It is otherwise useful on terminals for which the
back_color_erase (bce)
boolean terminfo capability does not apply,
when the chosen highlight colors do not affect the background, or when
EL is too slow or
causes too much flicker. The default is false
(i.e., the capability is omitted).

Note that boolean capabilities have no =... part. They
are omitted (i.e., false) by default and become true when specified.

See the Select Graphic Rendition (SGR) section in the
documentation of the text terminal that is used for permitted values
and their meaning
as character attributes. These substring values are
integers in decimal representation and can be concatenated with
semicolons. grep takes
care of assembling the result into a complete SGR
sequence (33[...m). Common values to concatenate include 1 for bold,
4 for underline, 5
for blink, 7 for inverse, 39 for default foreground
color, 30 to 37 for foreground colors, 90 to 97 for 16-color mode
foreground colors,
38;5;0 to 38;5;255 for 88-color and 256-color modes
foreground colors, 49 for default background color, 40 to 47 for
background colors, 100
to 107 for 16-color mode background colors, and 48;5;0
to 48;5;255 for 88-color and 256-color modes background colors.

LC_ALL, LC_COLLATE, LANG
These variables specify the locale for the LC_COLLATE
category, which determines the collating sequence used to interpret
range expressions
like [a-z].

LC_ALL, LC_CTYPE, LANG
These variables specify the locale for the LC_CTYPE
category, which determines the type of characters, e.g., which
characters are whitespace.

LC_ALL, LC_MESSAGES, LANG
These variables specify the locale for the LC_MESSAGES
category, which determines the language that grep uses for messages.
The default C
locale uses American English messages.

POSIXLY_CORRECT
If set, grep behaves as POSIX.2 requires; otherwise,
grep behaves more like other GNU programs. POSIX.2 requires that
options that follow
file names must be treated as file names; by default,
such options are permuted to the front of the operand list and are
treated as options.
Also, POSIX.2 requires that unrecognized options be
diagnosed as “illegal”, but since they are not really against the law
the default is to
diagnose them as “invalid”. POSIXLY_CORRECT also
disables _N_GNU_nonoption_argv_flags_, described below.

_N_GNU_nonoption_argv_flags_
(Here N is grep's numeric process ID.) If the ith
character of this environment variable's value is 1, do not consider
the ith operand of
grep to be an option, even if it appears to be one.
A shell can put this variable in the environment for each command it
runs, specifying
which operands are the results of file name wildcard
expansion and therefore should not be treated as options. This
behavior is available
only with the GNU C library, and only when
POSIXLY_CORRECT is not set.

EXIT STATUS
The exit status is 0 if selected lines are found, and 1 if not
found. If an error occurred the exit status is 2. (Note: POSIX error
handling code
should check for '2' or greater.)

COPYRIGHT
Copyright 1998-2000, 2002, 2005-2010 Free Software Foundation, Inc.

This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR
A PARTICULAR
PURPOSE.

BUGS
Reporting Bugs
Email bug reports to <bug-grep@gnu.org>, a mailing list
whose web page is <http://lists.gnu.org/mailman/listinfo/bug-grep>.
grep's Savannah bug
tracker is located at <http://savannah.gnu.org/bugs/?group=grep>.

Known Bugs
Large repetition counts in the {n,m} construct may cause grep
to use lots of memory. In addition, certain other obscure regular
expressions require
exponential time and space, and may cause grep to run out of memory.

Back-references are very slow, and may require exponential time.

SEE ALSO
Regular Manual Pages
awk(1), cmp(1), diff(1), find(1), gzip(1), perl(1), sed(1),
sort(1), xargs(1), zgrep(1), mmap(2), read(2), pcre(3), pcresyntax(3),
pcrepattern(3),
terminfo(5), glob(7), regex(7).

POSIX Programmer's Manual Page
grep(1p).

TeXinfo Documentation
The full documentation for grep is maintained as a TeXinfo
manual. If the info and grep programs are properly installed at your
site, the command

info grep

should give you access to the complete manual.

NOTES
GNU's not Unix, but Unix is a beast; its plural form is Unixen.



User Commands



> Mankind is a single body and each nation a part of that body. *We must
> never say "What does it matter to me if some part of the world is ailing?"
> If there is such an illness, we must concern ourselves with it as though we
> were having that illness.
>
> Mustafa Kemal Ataturk (1881-1938), founder and first President of the
> Republic of Turkey
>

Thank you for that quote. I find it very relevant and I will certainly
use the quote. Coming from Ataturk it is doubly valuable.

--
Dotan Cohen

http://gibberish.co.il
http://what-is-what.com
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Old 05-31-2011, 02:37 PM
Thomas Harold
 
Default Grep: show me this line and the next N lines?

On 5/31/2011 3:43 AM, Dotan Cohen wrote:
> On Tue, May 31, 2011 at 01:26, John R. Dennison<jrd@gerdesas.com> wrote:
>> On Tue, May 31, 2011 at 01:10:40AM +0300, Dotan Cohen wrote:
>>> Thanks, all. I did actually look at the grep manpage but after a few
>>> screenfuls it became tl;dr and I started just skimming. I suppose that
>>> I skimmed too fast!
>>
>> Um....
>>
>> It's the first option described.
>>
>
> I see now that the server's grep manpage (CentOS) does in fact put it
> right there at the top. I usually pull up manpages on localhost, not
> what I'm SSHing into, and on this Debian-Derived distro it is buried
> halfway down the third page of nine. That is interesting, and I'm sure
> that there is a lesson to be learned from that!
>

One help might be to use the slash key to search the man page.

/lines[enter]

Then use 'n' or 'N' to search forward/backward.
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Old 06-07-2011, 02:26 AM
Kenneth Porter
 
Default Grep: show me this line and the next N lines?

--On Tuesday, May 31, 2011 1:08 AM +0300 Dotan Cohen <dotancohen@gmail.com>
wrote:

> Can grep show the matching lines and the next N lines after a match?

If I'm just inspecting a file I use less and the "/" command to search up
to the next occurrence of a regular expression. Use the "?" command to
search backwards. See the man page for less for lots more options.


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