Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: read a file line by line
Top Forums Shell Programming and Scripting read a file line by line Post 302262097 by radoulov on Wednesday 26th of November 2008 10:34:48 AM
Old 11-26-2008
Quote:
Originally Posted by chebarbudo
[...]
So if you have time, could you help me on that:
1) I found no help about read's switch r.
From the bash builtin help:

Code:
$ help read
read: read [-ers] [-u fd] [-t timeout] [-p prompt] [-a array] [-n nchars] [-d delim] [name ...]
...
If the -r option is given, this signifies `raw' input, and
    backslash escaping is disabled.

Quote:
2) How can you write IFS= just before read, even without semi-colon to separate the commands? What's the purpose? Does it modify the value of IFS forever or just in the loop?
It's set only for the read call. Consider the following:

Code:
while IFS= read; do
  printf '\nread with empty IFS: |%s|\n' "$REPLY"
  read inside<<<"$REPLY"
  printf '\nread inside the loop: |%s|\n\n' "$inside"  
  printf "... so the current IFS is:\n"  
  od -bc<<<"$IFS" 
done<<<"   _x_   "

The output is:

Code:
read with empty IFS: |   _x_   |

read inside the loop: |_x_|

... so the current IFS is:
0000000 040 011 012 012
             \t  \n  \n
0000004

The combination space, tab and newline is the default value.
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

shell script to read a line in gps receiver log file and append that line to new file

Hi, I have gps receiver log..its giving readings .like below Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. GPSD,R=1 $GPGSV,3,1,11,08,16,328,40,11,36,127,00,28,33,283,39,20,11,165,00*71... (3 Replies)
Discussion started by: gudivada213
3 Replies

2. Shell Programming and Scripting

bash: read file line by line (lines have '\0') - not full line has read???

I am using the while-loop to read a file. The file has lines with null-terminated strings (words, actually.) What I have by that reading - just a first word up to '\0'! I need to have whole string up to 'new line' - (LF, 10#10, 16#A) What I am doing wrong? #make file 'grb' with... (6 Replies)
Discussion started by: alex_5161
6 Replies

3. Shell Programming and Scripting

Read file line by line and process the line to generate another file

Hi, i have file which contains data as below(Only sample shown, it may contain more data similar to the one shown here) i need to read this file line by line and generate an output file like the one below i.e based on N value the number of MSISDNs will vary, if N=1 then the following... (14 Replies)
Discussion started by: aemunathan
14 Replies

4. Shell Programming and Scripting

Shell script to read a text file line by line & process it...

Hi , I am trying to write an shell, which reads a text file (from a location) having a list of numbers of strictly 5 digits only ex: 33144 Now my script will check : 1) that each entry is only 5 digits & numeric only, no alphabets, & its not empty. 2)then it executes a shell script called... (8 Replies)
Discussion started by: new_to_shell
8 Replies

5. Shell Programming and Scripting

how to read the contents of two files line by line and compare the line by line?

Hi All, I'm trying to figure out which are the trusted-ips and which are not using a script file.. I have a file named 'ip-list.txt' which contains some ip addresses and another file named 'trusted-ip-list.txt' which also contains some ip addresses. I want to read a line from... (4 Replies)
Discussion started by: mjavalkar
4 Replies

6. Shell Programming and Scripting

Need a program that read a file line by line and prints out lines 1, 2 & 3 after an empty line...

Hello, I need a program that read a file line by line and prints out lines 1, 2 & 3 after an empty line... An example of entries in the file would be: SRVXPAPI001 ERRO JUN24 07:28:34 1775 REASON= 0000, PROCID= #E506 #1065: TPCIPPR, INDEX= 003F ... (8 Replies)
Discussion started by: Ferocci
8 Replies

7. Shell Programming and Scripting

How to read a text file line by line and insert into a database table?

I have a test file that I want to read and insert only certain lines into the the table based on a filter. 1. Rread the log file 12 Hours back Getdate() -12 Hours 2. Extract the following information on for lines that say "DUMP is complete" A. Date B. Database Name C.... (2 Replies)
Discussion started by: JolietJake
2 Replies

8. Shell Programming and Scripting

Bash script to read a file from particular line till required line and process

Hi All, Am trying to write wrapper shell/bash script on a utility tool for which i need to pass 2 files as arugment to execute utility tool. Wraper script am trying is to do with above metion 2 files. utility tool accepts : a. userinfo file : which contains username b. item file : which... (2 Replies)
Discussion started by: Optimus81
2 Replies

9. Shell Programming and Scripting

How to read file line by line and compare subset of 1st line with 2nd?

Hi all, I have a log file say Test.log that gets updated continuously and it has data in pipe separated format. A sample log file would look like: <date1>|<data1>|<url1>|<result1> <date2>|<data2>|<url2>|<result2> <date3>|<data3>|<url3>|<result3> <date4>|<data4>|<url4>|<result4> What I... (3 Replies)
Discussion started by: pat_pramod
3 Replies

10. Shell Programming and Scripting

With script bash, read file line per line starting at the end

Hello, I'm works on Ubuntu server My goal : I would like to read file line per line, but i want to started at the end of file. Currently, I use instructions : while read line; do COMMAND done < /var/log/apache2/access.log But, the first line, i don't want this. The file is long... (5 Replies)
Discussion started by: Fuziion
5 Replies

LEARN ABOUT MOJAVE

page_util_quote

page_util_quote(n)					      Parser generator tools						page_util_quote(n)

__________________________________________________________________________________________________________________________________________________

NAME

       page_util_quote - page character quoting utilities

SYNOPSIS

       package require page::util::quote  ?0.1?

       package require snit

       ::page::util::quote::unquote char

       ::page::util::quote::quote'tcl char

       ::page::util::quote::quote'tclstr char

       ::page::util::quote::quote'tclcom char

_________________________________________________________________

DESCRIPTION

       This package provides a few utility commands to convert characters into various forms.

API

       ::page::util::quote::unquote char
	      A  character,  as stored in an abstract syntax tree by a PEG processor (See the packages grammar::peg::interpreter, grammar::me, and
	      their relations), i.e. in some quoted form, is converted into the equivalent Tcl character. The character is returned as the  result
	      of the command.

       ::page::util::quote::quote'tcl char
	      This command takes a Tcl character (internal representation) and converts it into a string which is accepted by the Tcl parser, will
	      regenerate the character in question and is 7bit ASCII. The string is returned as the result of this command.

       ::page::util::quote::quote'tclstr char
	      This command takes a Tcl character (internal representation) and converts it into a string which is accepted by the Tcl  parser  and
	      will generate a human readable representation of the character in question.  The string is returned as the result of this command.

	      The  string  does not use any unprintable characters. It may use backslash-quoting. High UTF characters are quoted to avoid problems
	      with the still prevalent ascii terminals. It is assumed that the string will be used in a double-quoted environment.

       ::page::util::quote::quote'tclcom char
	      This command takes a Tcl character (internal representation) and converts it into a string which is accepted by the Tcl parser  when
	      used within a Tcl comment. The string is returned as the result of this command.

BUGS, IDEAS, FEEDBACK
       This  document,	will  undoubtedly  contain  bugs  and  other  problems.  Please report such in the category page of the Tcllib SF Trackers
       [http://sourceforge.net/tracker/?group_id=12883].  Please also report any ideas for enhancements you may have.

KEYWORDS

       page, parser generator, quoting, text processing

CATEGORY

       Page Parser Generator

COPYRIGHT

       Copyright (c) 2007 Andreas Kupries <andreas_kupries@users.sourceforge.net>

page									1.0							page_util_quote(n)
All times are GMT -4. The time now is 03:55 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy