Lets say I have a file abc.txt and it has about 35 million rows. I would like to take a sample of 100 random rows from that file for my testing purpose and write it to a file say test.txt.
How do I do this operation?
Thanks,
Sashank (9 Replies)
Hi!
I need to read in the first line from a text file (which will only ever have one line in it), so I tried this....
while read line
do
echo $line
done < $file
But this wasn't returning anything. So I tired a different file, which had multiple lines of text in it, and it returned... (2 Replies)
Hello,
I have got a script that reads a text file, and have got three problems that I an struggling with.
1. The script does not read the last line in the text file
2. within the second 'elif' within the script I included a 'break' - the script runs successfully (except for the first... (2 Replies)
Hi everyone,
I am writing a BASH shell script that I will use to process data files. I have a text file that contains the names of the files to be processed, for example:
cat filenames.txt
file1
file2
file3
file4
file5
What I would like to do is set up a FOR loop within my script... (2 Replies)
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)
I have list of files in a directory 'dir'. Each file is of type HTML. I need to read each file and get the string which starts with 'http' and write them in a new text file. How can i do this shell scripting?
file1.html
<head>
<url>http://www.google.com</url>
</head>
file2.html
<head>... (6 Replies)
performing this code to read from file and print each character in separate line
works well with ASCII encoded text
void
preprocess_file (FILE *fp)
{
int cc;
for (;;)
{ cc = getc (fp);
if (cc == EOF)
break;
printf ("%c\n", cc);
}
}
int
main(int... (1 Reply)
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)
i have a text file as belows, it includes 2 columns, 1st is the column name, 2nd is the file_name
data_file.txt
column_name file_name
col1 file1
col2 file2
col3 file1
col4 file1
col5 file2
now, i would like to... (4 Replies)
Discussion started by: tester111
4 Replies
LEARN ABOUT SUSE
rl
rl(1) User Commands rl(1)NAME
rl - Randomize Lines.
SYNOPSIS
rl [OPTION]... [FILE]...
DESCRIPTION
rl reads lines from a input file or stdin, randomizes the lines and outputs a specified number of lines. It does this with only a single
pass over the input while trying to use as little memory as possible.
-c, --count=N
Select the number of lines to be returned in the output. If this argument is omitted all the lines in the file will be returned in
random order. If the input contains less lines than specified and the --reselect option below is not specified a warning is printed
and all lines are returned in random order.
-r, --reselect
When using this option a single line may be selected multiple times. The default behaviour is that any input line will only be
selected once. This option makes it possible to specify a --count option with more lines than the file actually holds.
-o, --output=FILE
Send randomized lines to FILE instead of stdout.
-d, --delimiter=DELIM
Use specified character as a "line" delimiter instead of the newline character.
-0, --null
Input lines are terminated by a null character. This option is useful to process the output of the GNU find -print0 option.
-n, --line-number
Output lines are numbered with the line number from the input file.
-q, --quiet, --silent
Be quiet about any errors or warnings.
-h, --help
Show short summary of options.
-v, --version
Show version of program.
EXAMPLES
Some simple demonstrations of how rl can help you do everyday tasks.
Play a random sound after 4 minutes (perfect for toast):
sleep 240 ; play `find /sounds -name '*.au' -print | rl --count=1`
Play the 15 most recent .mp3 files in random order.
ls -c *.mp3 | head -n 15 | rl | xargs --delimiter='
' play
Roll a dice:
seq 6 | rl --count 2
Roll a dice 1000 times and see which number comes up more often:
seq 6 | rl --reselect --count 1000 | sort | uniq -c | sort -n
Shuffle the words of a sentence:
echo -n "The rain in Spain stays mainly in the plain."
| rl --delimiter=' ';echo
Find all movies and play them in random order.
find . -name '*.avi' -print0 | rl -0 | xargs -n 1 -0 mplayer
Because -0 is used filenames with spaces (even newlines and other unusual characters) in them work.
BUGS
The program currently does not have very smart memory management. If you feed it huge files and expect it to fully randomize all lines it
will completely read the file in memory. If you specify the --count option it will only use the memory required for storing the specified
number of lines. Improvements on this area are on the TODO list.
The program uses the rand() system random function. This function returns a number between 0 and RAND_MAX, which may not be very large on
some systems. This will result in non-random results for files containing more lines than RAND_MAX.
Note that if you specify multiple input files they are randomized per file. This is a different result from when you cat all the files and
pipe the result into rl.
COPYRIGHT
Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 Arthur de Jong.
This is free software; see the license for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.
Version 0.2.7 Jul 2008 rl(1)