Hi ,
I am currently using the while loop in bash shell, as follows.
while read line
do
echo $line
done < file.txt
However, i want to use the while loop on file.txt, which will read the file with 4 lines of gap.
Ex- if file.txt is a file of 100 lines, then i want to use the loop such... (3 Replies)
Is this possible?
I have a for loop in a shell script reading a list, but I want each line to be a loop, not each thing with a space.
Here is the example:
HOSTLIST="\
1.2.3.4 serverA
1.2.3.5 serverB"
for NBUHOST in `echo $HOSTLIST`
do
ssh ${SERVERNAME} "echo "${NBUHOST}"... (3 Replies)
hi,
this is my script #!/bin/ksh
cat temp_file.dat | while read line
do
read test
if ]; then
break
else echo "ERROR"
fi
done
when i execute this code , the script does wait for the user input . it directly prints "ERROR" and terminates after the no. of times as there... (3 Replies)
Hi all,
Sorry if someone has answered something like this already, but I have a problem. I am not brilliant with "awk" but think it should be the command to use to get what I am after.
I have 2 files:
job-file (several hundred lines like):
1018003,LONG MU WAN,1113S
1018004,LONG MU... (4 Replies)
Hello All,
i am a newbie and need some help when reading a csv file in a bourne shell script. I want to read 10 lines, then wait for a minute and then do a reading of another 10 lines and so on in the same way. I want to do this till the end of file.
Any inputs are appreciated
... (3 Replies)
Dear all,
I have a file like this:
imput
scaffold_0 1
scaffold_0 10000
scaffold_0 20000
scaffold_0 25000
scaffold_1 1
scaffold_1 10000
scaffold_1 20000
scaffold_1 23283
and I want the output like this:
scaffold_0 1 scaffold_0 10000
scaffold_0 10000 scaffold_0 20000... (6 Replies)
I have a file which has following content:
NAME=ora.DG1.dg
TYPE=ora.diskgroup.type
TARGET=ONLINE
STATE=ONLINE
NAME=ora.DG2.dg
TYPE=ora.diskgroup.type
TARGET=ONLINE
STATE=ONLINE
NAME=ora.DG3.dg
TYPE=ora.diskgroup.type
TARGET=ONLINE
STATE=ONLINE
NAME=ora.DG4.dg... (7 Replies)
I have three files of varying lengths and different number of columns. How can I paste all three with all columns aligned?
File1
----
123
File2
----
234
345
678
File3
----
456
789
Output should look like:
123 234 456
345 789 (6 Replies)
Discussion started by: Un1xNewb1e
6 Replies
LEARN ABOUT CENTOS
perldbmfilter
PERLDBMFILTER(1) Perl Programmers Reference Guide PERLDBMFILTER(1)NAME
perldbmfilter - Perl DBM Filters
SYNOPSIS
$db = tie %hash, 'DBM', ...
$old_filter = $db->filter_store_key ( sub { ... } );
$old_filter = $db->filter_store_value( sub { ... } );
$old_filter = $db->filter_fetch_key ( sub { ... } );
$old_filter = $db->filter_fetch_value( sub { ... } );
DESCRIPTION
The four "filter_*" methods shown above are available in all the DBM modules that ship with Perl, namely DB_File, GDBM_File, NDBM_File,
ODBM_File and SDBM_File.
Each of the methods works identically, and is used to install (or uninstall) a single DBM Filter. The only difference between them is the
place that the filter is installed.
To summarise:
filter_store_key
If a filter has been installed with this method, it will be invoked every time you write a key to a DBM database.
filter_store_value
If a filter has been installed with this method, it will be invoked every time you write a value to a DBM database.
filter_fetch_key
If a filter has been installed with this method, it will be invoked every time you read a key from a DBM database.
filter_fetch_value
If a filter has been installed with this method, it will be invoked every time you read a value from a DBM database.
You can use any combination of the methods from none to all four.
All filter methods return the existing filter, if present, or "undef" if not.
To delete a filter pass "undef" to it.
The Filter
When each filter is called by Perl, a local copy of $_ will contain the key or value to be filtered. Filtering is achieved by modifying the
contents of $_. The return code from the filter is ignored.
An Example: the NULL termination problem.
DBM Filters are useful for a class of problems where you always want to make the same transformation to all keys, all values or both.
For example, consider the following scenario. You have a DBM database that you need to share with a third-party C application. The C
application assumes that all keys and values are NULL terminated. Unfortunately when Perl writes to DBM databases it doesn't use NULL
termination, so your Perl application will have to manage NULL termination itself. When you write to the database you will have to use
something like this:
$hash{"$key "} = "$value ";
Similarly the NULL needs to be taken into account when you are considering the length of existing keys/values.
It would be much better if you could ignore the NULL terminations issue in the main application code and have a mechanism that
automatically added the terminating NULL to all keys and values whenever you write to the database and have them removed when you read from
the database. As I'm sure you have already guessed, this is a problem that DBM Filters can fix very easily.
use strict;
use warnings;
use SDBM_File;
use Fcntl;
my %hash;
my $filename = "filt";
unlink $filename;
my $db = tie(%hash, 'SDBM_File', $filename, O_RDWR|O_CREAT, 0640)
or die "Cannot open $filename: $!
";
# Install DBM Filters
$db->filter_fetch_key ( sub { s/ $// } );
$db->filter_store_key ( sub { $_ .= "