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Top Forums UNIX for Beginners Questions & Answers How to make a loop to read the input from a file part by part? Post 303038091 by arun_adm on Saturday 24th of August 2019 04:02:45 PM
Old 08-24-2019
How to make a loop to read the input from a file part by part?

Hi All,

We've a VDI infrastructure in AWS (AWS workspaces) and we're planning to automate the process of provisioning workspaces. Instead of going to GUI console, and launching workspaces by selecting individual users is little time consuming. Thus, I want to create them in bunches from AWS CLI (installed on centos 7). To achieve this I've created below shell script to launch the workspaces from CLI with least efforts. Please note, the ws-userlist.txt has a list of 60 users, one word per line.

Code:
for i in `cat ws-userlist.txt`;do command-to-create-workspaces DirectoryId=<directoryID>,UserName=$i,BundleId=<bundleID>;done

Now, here, there is a limitation of above workspace creation command. It can only build maximum 25 workspaces at one execution. I wonder if there any way to make the loop read the ws-userlist.txt in such a way that it read the first 25 users and take it as input for the command and execute it. once the it get executed, loop should go back to the input file, and read next set of 25 users and execute the command. Once it get executed, loop again go back to input file, and read the last 10 usernames and run the command.
Please note, username count could vary.Sometime I may have a list of 30, sometimes it could be 55.

I've basic knowledge of shell scripting. Need your expert help on this.
Thanks in advance.
 

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AnyEvent::I3(3pm)					User Contributed Perl Documentation					 AnyEvent::I3(3pm)

NAME
AnyEvent::I3 - communicate with the i3 window manager VERSION
Version 0.08 SYNOPSIS
This module connects to the i3 window manager using the UNIX socket based IPC interface it provides (if enabled in the configuration file). You can then subscribe to events or send messages and receive their replies. use AnyEvent::I3 qw(:all); my $i3 = i3(); $i3->connect->recv or die "Error connecting"; say "Connected to i3"; my $workspaces = $i3->message(TYPE_GET_WORKSPACES)->recv; say "Currently, you use " . @{$workspaces} . " workspaces"; ...or, using the sugar methods: use AnyEvent::I3; my $workspaces = i3->get_workspaces->recv; say "Currently, you use " . @{$workspaces} . " workspaces"; EXPORT
$i3 = i3([ $path ]); Creates a new "AnyEvent::I3" object and returns it. "path" is an optional path of the UNIX socket to connect to. It is strongly advised to NOT specify this unless you're absolutely sure you need it. "AnyEvent::I3" will automatically figure it out by querying the running i3 instance on the current DISPLAY which is almost always what you want. SUBROUTINES
/METHODS $i3 = AnyEvent::I3->new([ $path ]) Creates a new "AnyEvent::I3" object and returns it. "path" is an optional path of the UNIX socket to connect to. It is strongly advised to NOT specify this unless you're absolutely sure you need it. "AnyEvent::I3" will automatically figure it out by querying the running i3 instance on the current DISPLAY which is almost always what you want. $i3->connect Establishes the connection to i3. Returns an "AnyEvent::CondVar" which will be triggered with a boolean (true if the connection was established) as soon as the connection has been established. if ($i3->connect->recv) { say "Connected to i3"; } $i3->subscribe(\%callbacks) Subscribes to the given event types. This function awaits a hashref with the key being the name of the event and the value being a callback. my %callbacks = ( workspace => sub { say "Workspaces changed" } ); if ($i3->subscribe(\%callbacks)->recv->{success}) say "Successfully subscribed"; } The special callback with name "_error" is called when the connection to i3 is killed (because of a crash, exit or restart of i3 most likely). You can use it to print an appropriate message and exit cleanly or to try to reconnect. my %callbacks = ( _error => sub { my ($msg) = @_; say "I am sorry. I am so sorry: $msg"; exit 1; } ); $i3->subscribe(\%callbacks)->recv; $i3->message($type, $content) Sends a message of the specified "type" to i3, possibly containing the data structure "content" (or "content", encoded as utf8, if "content" is a scalar), if specified. my $reply = $i3->message(TYPE_COMMAND, "reload")->recv; if ($reply->{success}) { say "Configuration successfully reloaded"; } SUGAR METHODS
These methods intend to make your scripts as beautiful as possible. All of them automatically establish a connection to i3 blockingly (if it does not already exist). get_workspaces Gets the current workspaces from i3. my $ws = i3->get_workspaces->recv; say Dumper($ws); get_outputs Gets the current outputs from i3. my $outs = i3->get_outputs->recv; say Dumper($outs); get_tree Gets the layout tree from i3 (>= v4.0). my $tree = i3->get_tree->recv; say Dumper($tree); get_marks Gets all the window identifier marks from i3 (>= v4.1). my $marks = i3->get_marks->recv; say Dumper($tree); command($content) Makes i3 execute the given command my $reply = i3->command("reload")->recv; die "command failed" unless $reply->{success}; AUTHOR
Michael Stapelberg, "<michael at stapelberg.de>" BUGS
Please report any bugs or feature requests to "bug-anyevent-i3 at rt.cpan.org", or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=AnyEvent-I3 <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=AnyEvent-I3>. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes. SUPPORT
You can find documentation for this module with the perldoc command. perldoc AnyEvent::I3 You can also look for information at: o RT: CPAN's request tracker http://rt.cpan.org/NoAuth/Bugs.html?Dist=AnyEvent-I3 <http://rt.cpan.org/NoAuth/Bugs.html?Dist=AnyEvent-I3> o The i3 window manager website <http://i3.zekjur.net/> ACKNOWLEDGEMENTS
LICENSE AND COPYRIGHT
Copyright 2010 Michael Stapelberg. This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License. See http://dev.perl.org/licenses/ for more information. perl v5.14.2 2012-12-15 AnyEvent::I3(3pm)
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