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Top Forums Shell Programming and Scripting displaying nth line of a file dynamically Post 302451005 by deanamrita on Sunday 5th of September 2010 08:22:45 AM
Old 09-05-2010
displaying nth line of a file dynamically

Hi,

I have a file split.txt with the following contents

Code:
one
two
three
four
five

Suppose if i want to display contents of line 3, I know this could be achieved using the command
Code:
sed -n '3p' split.txt

But I need the line number to be decided dynamically like
Code:
a=3
sed -n '$ap' split.txt

But the above command doesnt work as sed -n '3p' split.txt. So how could I display the contents of a line whose line number is decided dynamically (or) how could I display the contents of a file using line numbers

Last edited by Scott; 09-05-2010 at 09:29 AM.. Reason: Please use code tags
 

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SPLIT(1)						    BSD General Commands Manual 						  SPLIT(1)

NAME
split -- split a file into pieces SYNOPSIS
split -d [-l line_count] [-a suffix_length] [file [prefix]] split -d -b byte_count[K|k|M|m|G|g] [-a suffix_length] [file [prefix]] split -d -n chunk_count [-a suffix_length] [file [prefix]] split -d -p pattern [-a suffix_length] [file [prefix]] DESCRIPTION
The split utility reads the given file and breaks it up into files of 1000 lines each (if no options are specified), leaving the file unchanged. If file is a single dash ('-') or absent, split reads from the standard input. The options are as follows: -a suffix_length Use suffix_length letters to form the suffix of the file name. -b byte_count[K|k|M|m|G|g] Create split files byte_count bytes in length. If k or K is appended to the number, the file is split into byte_count kilobyte pieces. If m or M is appended to the number, the file is split into byte_count megabyte pieces. If g or G is appended to the num- ber, the file is split into byte_count gigabyte pieces. -d Use a numeric suffix instead of a alphabetic suffix. -l line_count Create split files line_count lines in length. -n chunk_count Split file into chunk_count smaller files. -p pattern The file is split whenever an input line matches pattern, which is interpreted as an extended regular expression. The matching line will be the first line of the next output file. This option is incompatible with the -b and -l options. If additional arguments are specified, the first is used as the name of the input file which is to be split. If a second additional argument is specified, it is used as a prefix for the names of the files into which the file is split. In this case, each file into which the file is split is named by the prefix followed by a lexically ordered suffix using suffix_length characters in the range ``a-z''. If -a is not speci- fied, two letters are used as the suffix. If the prefix argument is not specified, the file is split into lexically ordered files named with the prefix ``x'' and with suffixes as above. ENVIRONMENT
The LANG, LC_ALL, LC_CTYPE and LC_COLLATE environment variables affect the execution of split as described in environ(7). EXIT STATUS
The split utility exits 0 on success, and >0 if an error occurs. SEE ALSO
csplit(1), re_format(7) STANDARDS
The split utility conforms to IEEE Std 1003.1-2001 (``POSIX.1''). HISTORY
A split command appeared in Version 3 AT&T UNIX. BUGS
The maximum line length for matching patterns is 65536. BSD
May 9, 2013 BSD
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