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Old 04-17-2013, 07:25 PM   #1
igorza
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Registered: Apr 2013
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Shell script to find a string and print x lines before and y lines after the string


I have a file like this:

-----------------------------------

Mode: 5

priority: 1
status: on
version: 1.0.1
description: it is ok
short description: ok
value: D
target: a23
-----------------------------------

Mode: 22

priority: 4
status: on
version: 1.3.1
description: it is the best
short description: the best
value: G
target: b13

-----------------------------------

Mode: 15

priority: 2
status: off
version: 2.0.3
description: it isn't ok
short description: nok
value: D
target: b43

-----------------------------------

Mode: 23

priority: 1
status: off
version: 3.2.3
description: description
short description: desc
value: A
target: f27

-----------------------------------


I want to save to file only parts/sections where value is D (value: D), so new file should be:
-----------------------------------

Mode: 5

priority: 1
status: on
version: 1.0.1
description: it is ok
short description: ok
value: D
target: a23
-----------------------------------

Mode: 15

priority: 2
status: off
version: 2.0.3
description: it isn't ok
short description: nok
value: D
target: b43

-----------------------------------

Idea is to find string »value: D« and to print this line, plus 9 lines above and 2 lines below, and search next »value: D« string… using awk or sed. The string is repeated many times in the file. Any help?
 
Old 04-17-2013, 08:38 PM   #2
chrism01
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Code:
grep -A1 -B9 --no-group-separator 'value: D' t.t
If you use -A2 with that data, you'll get duplicated '------------' lines.
EG your first data block has no blank line at the end, the others do.
If you give it a blank line, then -A2 is fine; see http://linux.die.net/man/1/grep
 
1 members found this post helpful.
Old 04-17-2013, 09:37 PM   #3
towheedm
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I've been searching for a way to get rid of the group separator for a while now. This is not documented in the manpages and does not show up with grep --help:

Code:
grep --help
Usage: grep [OPTION]... PATTERN [FILE]...
Search for PATTERN in each FILE or standard input.
PATTERN is, by default, a basic regular expression (BRE).
Example: grep -i 'hello world' menu.h main.c

Regexp selection and interpretation:
  -E, --extended-regexp     PATTERN is an extended regular expression (ERE)
  -F, --fixed-strings       PATTERN is a set of newline-separated fixed strings
  -G, --basic-regexp        PATTERN is a basic regular expression (BRE)
  -P, --perl-regexp         PATTERN is a Perl regular expression
  -e, --regexp=PATTERN      use PATTERN for matching
  -f, --file=FILE           obtain PATTERN from FILE
  -i, --ignore-case         ignore case distinctions
  -w, --word-regexp         force PATTERN to match only whole words
  -x, --line-regexp         force PATTERN to match only whole lines
  -z, --null-data           a data line ends in 0 byte, not newline

Miscellaneous:
  -s, --no-messages         suppress error messages
  -v, --invert-match        select non-matching lines
  -V, --version             print version information and exit
      --help                display this help and exit
      --mmap                ignored for backwards compatibility

Output control:
  -m, --max-count=NUM       stop after NUM matches
  -b, --byte-offset         print the byte offset with output lines
  -n, --line-number         print line number with output lines
      --line-buffered       flush output on every line
  -H, --with-filename       print the filename for each match
  -h, --no-filename         suppress the prefixing filename on output
      --label=LABEL         print LABEL as filename for standard input
  -o, --only-matching       show only the part of a line matching PATTERN
  -q, --quiet, --silent     suppress all normal output
      --binary-files=TYPE   assume that binary files are TYPE;
                            TYPE is `binary', `text', or `without-match'
  -a, --text                equivalent to --binary-files=text
  -I                        equivalent to --binary-files=without-match
  -d, --directories=ACTION  how to handle directories;
                            ACTION is `read', `recurse', or `skip'
  -D, --devices=ACTION      how to handle devices, FIFOs and sockets;
                            ACTION is `read' or `skip'
  -R, -r, --recursive       equivalent to --directories=recurse
      --include=FILE_PATTERN  search only files that match FILE_PATTERN
      --exclude=FILE_PATTERN  skip files and directories matching FILE_PATTERN
      --exclude-from=FILE   skip files matching any file pattern from FILE
      --exclude-dir=PATTERN  directories that match PATTERN will be skipped.
  -L, --files-without-match  print only names of FILEs containing no match
  -l, --files-with-matches  print only names of FILEs containing matches
  -c, --count               print only a count of matching lines per FILE
  -T, --initial-tab         make tabs line up (if needed)
  -Z, --null                print 0 byte after FILE name

Context control:
  -B, --before-context=NUM  print NUM lines of leading context
  -A, --after-context=NUM   print NUM lines of trailing context
  -C, --context=NUM         print NUM lines of output context
  -NUM                      same as --context=NUM
      --color[=WHEN],
      --colour[=WHEN]       use markers to highlight the matching strings;
                            WHEN is `always', `never', or `auto'
  -U, --binary              do not strip CR characters at EOL (MSDOS)
  -u, --unix-byte-offsets   report offsets as if CRs were not there (MSDOS)

`egrep' means `grep -E'.  `fgrep' means `grep -F'.
Direct invocation as either `egrep' or `fgrep' is deprecated.
With no FILE, or when FILE is -, read standard input.  If less than two FILEs
are given, assume -h.  Exit status is 0 if any line was selected, 1 otherwise;
if any error occurs and -q was not given, the exit status is 2.

Report bugs to: bug-grep@gnu.org
GNU Grep home page: <http://www.gnu.org/software/grep/>
General help using GNU software: <http://www.gnu.org/gethelp/>
Using GNU grep 2.6.3.
 
Old 04-17-2013, 10:35 PM   #4
chrism01
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The wonders of Google
Somebody read the src & I found his post

Search "grep suppress group separator"

1st result http://stackoverflow.com/questions/2...-context-lines
 
Old 04-17-2013, 10:52 PM   #5
towheedm
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Thanks. Did not get around to searching. I was trying to do it with sed also using http://www.grymoire.com/Unix/Sed.html#toc-uh-56.
 
Old 04-18-2013, 03:00 AM   #6
igorza
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Registered: Apr 2013
Posts: 2

Original Poster
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Thank you all.
 
Old 04-18-2013, 04:31 PM   #7
David the H.
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The info pages of most commands have more detailed information than the man pages. You'll find the --no-group-separator listed there. There's also --group-separator=STRING' if you want to change it to something other than the default.

Do note that these are gnu grep extensions, and were only added fairly recently at that.
 
  


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