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Top Forums Shell Programming and Scripting Extract a specific line from a stream Post 302486418 by Oddant on Saturday 8th of January 2011 11:47:18 AM
Old 01-08-2011
Error Extract a specific line from a stream

Hello,

I'm trying to code a bash script and I was wondering how to extract a specific line from a stream.

E.g.
My file "file" contains three lines and i'd like to find a function f which returns after execution a specific line like the second line, which would be :

Code:
f(file, 2) = Second line of the file (String form)



I was trying to make so with grep, less, cat, more, ... but I can't figure oout any way to make it happens.

Ok to be more precise, I wanna print the name of the n-file in the "ls -1" stream. For example if I type "ls -1", here's the output:

Code:
file1
file2
file3



My script prompts the user to specify the name of the file n he wants to read.
If the user type 2, the new output would be "file2" (string form).
The final line instruction would be something like :

Code:
f( $(ls -1) , n) = the n-line of the output of "ls -1"


Ok so much lines for a little trouble.
I hope someone knows a solution for it, and since i'm french and i'm not sure my problem is well-posted feel free to ask other questions.

Thanks Smilie
 

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LIBBASH(7)							  libbash Manual							LIBBASH(7)

NAME
libbash -- A bash shared libraries package. DESCRIPTION
libbash is a package that enables bash dynamic-like shared libraries. Actually its a tool for managing bash scripts whose functions you may want to load and use in scripts of your own. It contains a 'dynamic loader' for the shared libraries ( ldbash(1)), a configuration tool (ldbashconfig(8)), and some libraries. Using ldbash(1) you are able to load loadable bash libraries, such as getopts(1) and hashstash(1). A bash shared library that can be loaded using ldbash(1) must answer 4 requirments: 1. It must be installed in $LIBBASH_PREFIX/lib/bash (default is /usr/lib/bash). 2. It must contain a line that begins with '#EXPORT='. That line will contain (after the '=') a list of functions that the library exports. I.e. all the function that will be usable after loading that library will be listed in that line. 3. It must contain a line that begins with '#REQUIRE='. That line will contain (after the '=') a list of bash libraries that are required for our library. I.e. every bash library that is in use in our bash library must be listed there. 4. The library must be listed (For more information, see ldbashconfig(8)). Basic guidelines for writing library of your own: 1. Be aware, that your library will be actually sourced. So, basically, it should contain (i.e define) only functions. 2. Try to declare all variables intended for internal use as local. 3. Global variables and functions that are intended for internal use (i.e are not defined in '#EXPORT=') should begin with: __<library_name>_ For example, internal function myfoosort of hashstash library should be named as __hashstash_myfoosort This helps to avoid conflicts in global name space when using libraries that come from different vendors. 4. See html manual for full version of this guide. AUTHORS
Hai Zaar <haizaar@haizaar.com> Gil Ran <ril@ran4.net> SEE ALSO
ldbash(1), ldbashconfig(8), getopts(1), hashstash(1) colors(1) messages(1) urlcoding(1) locks(1) Linux Epoch Linux
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