App-Cheats
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sudo usermod -a -G docker $USER
sudo su $USER # To avoid restarting for groups to take effect
docker pull mailserver/docker-mailserver:latest
# Check docker processes
docker ps
ctop
#############################################################
## Docker Setup
#############################################################
# Enable cgroups in ubuntu (for docker)
sudo vi /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash systemd.unified_cgroup_hierarchy=1 cgroup_enable=memory cgroup_memory=1"
sudo update-grub
reboot
# Check if cgroups is enabled (ubuntu)
cat /proc/cmdline
# Check if using cgroups v1:
ls /sys/fs/cgroup
blkio cpuacct cpuset freezer memory net_cls,net_prio perf_event rdma unified
cpu cpu,cpuacct devices hugetlb net_cls net_prio pids systemd
# Check if using cgroups v2:
ls /sys/fs/cgroup
cgroup.controllers cgroup.max.descendants cgroup.stat cgroup.threads system.slice
cgroup.max.depth cgroup.procs cgroup.subtree_control init.scope user.slice
#############################################################
## Docker Build
#############################################################
# Build a docker image based on the Dockerfile
cd ~/tmp/learning_docker/02-*
docker build .
docker images
# EXPOSE 80 in Dockerfile does nothing
docker run -p 3000:80 <IMAGE_ID>
http://localhost:3000/
docker ps
docker stop <CONTAINER_ID>
# Run interactive container (perl shell)
docker run -it perl
docker run -it py-max
# Restart container for CLI
docker start -a -i 99150a04a616
# Run interactive container (bash shell)
docker run -it perl bash
# Go inside a running container.
docker container exec -it feedback-app bash
# Build updated perl image.
docker build -t my-perl .
docker run my-perl -E 'say $^V'
# Rename a docker container
docker container rename <CONTAINER_ID> my-perl-container
# Restart a container
docker container start -a my-perl-container
#############################################################
## Docker Dockerfile Commands
#############################################################
# Dockerfile commands:
# These are executed only during a BUILD.
FROM perl
WORKDIR /app
COPY . /app
RUN echo "Building the image now"
RUN perl -E 'say "Image uses perl version: $^V"'
# Dockerfile commands:
# These are executed only during a RUN.
CMD [ "ls" ]
CMD [ "echo", "Run the container now" ]
CMD [ "perl", "my.pl" ]
#
ENTRYPOINT [ "perl" ]
docker run <IMAGE_ID> -E 'say $^V'
# Dockerfile commands:
# COPY can be controlled by
cat .dockerignore
.git*
node_modules
#############################################################
## Docker Images/Containers
#############################################################
# Images and containers.
# Image - blueprint.
# Container - instance of image.
# Get an image with perl inside.
docker run perl perl -E 'say $^V'
#
# Or in 2 steps.
docker pull perl
docker images
docker run <IMAGE_ID> perl -E 'say $^V'
docker run -it perl:5.38-slim perl -E 'say 123'
# Dump the contents of an image.
docker image inspect my-perl
# Copy file to/from a container.
# For config files.
docker cp youthful_brown:/app/.bashrc .
#############################################################
## Linux Commands - last, lastlog
#############################################################
# Display all users that are logged in
last
last -i # IP address
# View all last login times for all users
lastlog
lastlog | NOT "Never logged" | AND "Jan\s+(9|10)"
# View last login for a user
last xbe4092
#############################################################
## Linux Commands - ld
#############################################################
# Check if library can be found (gnu make)
ld -libmy.a
#############################################################
## Linux Commands - ldd, ldconfig
#############################################################
# Print shared library dependancies (Added: 2017-10-04 02:02:51 PM)
ldd `which svn`
# configure dynamic library linker run-time bindings (Added: 2017-10-04 02:11:12 PM)
ldconfig -v
# Search locations of system libraries (DES, Setup new machine)
ldconfig -p | grep my_lib
#############################################################
## Linux Commands - libreoffice
#############################################################
# Convert excel to csv on the command line.
# https://help.libreoffice.org/latest/en-GB/text/shared/guide/csv_params.html
# 76 - UTF-8 encoding.
# 44 - Comma.
# 34 - Double quote.
my $csv_format = qq(csv:"Text - txt - csv (StarCalc)":44,34,76);
my $command = qq(libreoffice --headless --convert-to $csv_format $excel_file);
system $command;
die if $?;
#############################################################
## Linux Commands - locate
#############################################################
# Search for a c header file (DES)
sudo updatedb # If added from apt-get
locate my_header
#############################################################
## Linux Commands - ls, ll
#############################################################
# Apply a character class to list (ls files)
ll *2[1-3]
#############################################################
## Linux Commands - mail
#############################################################
# Email the contents of a file to someone
echo $(cat mail.dat) | mail -s "File Name" timofey.potapov@pw.utc.com
# Print fixed width (monospace) emails
cat batch_report.formatted | perl -le 'print "<html><body><pre>\n", <>, "\n</pre></body></html>"' | mail -s "html report -a " -a "Content-Type: text/html" timofey.potapov@pw.utc.com
# Send email with a file as an attachment
cat ENV_linux.txt | mail -s "attachement" -a "Content-Type: html" timofey.potapov@pw.utc.com
# Send mail from another bench
ssh potapov@lnxbr25 'cat ~/bin/date.dat | mail -s "subject" timofey.potapov@pw.utc.com'
# Find out which benches can send emails
run_on_all_benches.p 'echo "on bench `uname -n`" | mail -s "`uname -n`" melvin.williams@pw.utc.com'
# View emails on bench
mail
# Delete single email of yours on bench
mail
>> d
# Delete all your emails on bench
mail
>> d*
#############################################################
## Linux Commands - man
#############################################################
# Show the location of all man page (manual/pod)
man --where --all date
# read a specific man page when there are many with the same name (Added: 2017-11-02 09:04:16 AM)
man -k readlink
man 2 readlink
#############################################################
## Linux Commands - mktemp
#############################################################
# Create a randomly named temp file.
mktemp
PS1+=" "
}
#############################################################
## Linux Commands - xxd
#############################################################
# Convert a binary file to hex
xxd NVM_EDF_CHA.dat > tmp_file
# Convert a hex file to binary
xxd -r tmp_file > tmp.bin
# Open a binary file in hex with vim
vi <(xxd tmp.bin)
#############################################################
## Linux Commands - ypcat
#############################################################
# View password file on main server (yellow page cat)
ypcat passwd
# Add ypcat passwd command if missing
vi /var/yp/nicknames
# add entry: passwd passwd.byname
# Return users which are found in the yellow pages password file
cat user_deletion_list | perl -ne 'print `ypcat passwd | grep $_` ' > found_in_yp
# Remove/Delete a user account
1. Check username in Outlook (CTRL-K)
2. Check username in Yellow Pages (ypcat passwd | grep username)
3. Go to file server
sudo userdel -r username # -r does this: sudo rm -rf username
sudo make -C /var/yp
#############################################################
## Linux Commands - yppasswd
#############################################################
# Change your password
yppasswd
#############################################################
## Linux Commands - zero
#############################################################
# Clear NVM/flash memory (from start to and including the end address)
zero -p ppa -s 0xSTART_ADDRESS -e 0xEND_ADDRESS
#############################################################
## Linux Accounts
#############################################################
# Check when a users account was created (good unless file was updated or touched)
ll ~SOME_USER/.bash_logout
# Check when a users account was created (good unless home account changed)
ll -d ~SOME_USER
echo ~SOME_USER | perl -lne 'print for -M,-C,-A'
#############################################################
## Linux Hardware
#############################################################
# View how many processors are on a machine/bench
cat proc/cpuinfo
cat /proc/cpuinfo | perl -ln0777e "print ~~split qq(\n\n)"
nproc
# Find out the service tag code of a machine (Bob)
# That is the same as the serial number
# Used for compability purposes (such as when getting new drives)
/usr/sbin/dmidecode | perl -ln00e 'print if /System Information/'
# Find out easily how many cpu there are (a command)
lscpu
# Check if using intel or AMD. (linux)
lscpu | grep 'Vendor ID'
# Add module to kernel (DES,UI,insert,library)
insmod /lib/modules/2.6.11/kernel/fs/fat/fat.ko
modprobe msdos
# Find out version of debian you are running (DES)
cat /etc/debian_version
# Check processor family (DES,UI)
grep "cpu family" /proc/cpuinfo
# Cpu family of "6" means use "Pentium-Pro"
# Change boot loader to use certain cpu's (DES,UI,Mark,shielding)
cd /boot/grub
sudo vi grub.cfg
/\Vlinux /boot/vmlinuz-3.16.51+20180205+1524
/\Vlinux /boot/vmlinuz-3.16.51+20180205+1524
# Add this to
isolcpus=0,1,2,3,4,5,6,7,8,9
cat /proc/cmdline
# Check timer frequency (DES,UI,CONFIG_HZ_1000)
cat /usr/src/linux.config | OR CONFIG_COMPAT_BRK CONFIG_HZ_PERIODIC CONFIG_X86_GENERIC CONFIG_SCHED_SMT CONFIG_HZ_1000
# find biggest binary number on the machine
perl -lE '@a=split //, sprintf "%b", ~~-1; print @a'
perl -lE '@a=split //, sprintf "%b", ~~-1; print scalar @a'
# Size of an integer on this system
perl -le 'print length pack "i"'
#############################################################
## Linux File Properties - General
perl -MCwd -le 'print getcwd'
# Get absolute path to a file (works same for link and regular files,DES)
perl -MCwd=realpath -le '$_="file"; print realpath($_)'
#############################################################
## Perl Modules - DateTime
#############################################################
# Create expiration dates (Start of tomorrow,start of next week)
perl -MDateTime -E '$dt = DateTime->now; say $dt->add(days => 1)->truncate(to => "day" )'
# 2021-08-06T00:00:00
perl -MDateTime -E '$dt = DateTime->now; say $dt->add(weeks => 1)->truncate(to => "local_week" )'
# 2021-08-08T00:00:00
# Truncate date to start of this week (Monday).
perl -MDateTime -E '$dt = DateTime->now; say $dt->truncate(to => "week" )->strftime("%e %b %Y")'
# Truncate date to end of 3 weeks from now on a Friday.
perl -MDateTime -E '$dt = DateTime->now; say $dt->truncate(to => "week" )->add(weeks => 3, days => 4)->strftime("%e %b %Y")'
#############################################################
## Perl Modules - Data::DPath
#############################################################
# Recurse through a data structure and print matches.
perl -MData::DPath -Mojo -E 'my $data = {a => [0, {complex => 1}]}; say "\nBefore:"; say r $data; for my $node ( grep {ref} Data::DPath->match($data, "//") ){ say "Tying: $node: " . r $node}'
#
# Before:
# {
# "a" => [
# 0,
# {
# "complex" => 1
# }
# ]
# }
#
# Tying: ARRAY(0xb400007e98818a28): [
# 0,
# {
# "complex" => 1
# }
# ]
#
# Tying: HASH(0xb400007e98818698): {
# "complex" => 1
# }
#
# Tying: HASH(0xb400007e988291f0): {
# "a" => [
# 0,
# {
# "complex" => 1
# }
# ]
# }
# Show where a complex data structure is being updated.
perl -MData::DPath -MCarp=longmess -MTie::Watch -Mojo -E 'my $data = {a => [0, {complex => 1}]}; say "\nBefore:"; say r $data; for my $node ( grep {ref} Data::DPath->match($data, "//") ){ say "Tying: $node"; Tie::Watch->new( -variable => $node, -stor...
#############################################################
## Perl Modules - Data::Dumper
#############################################################
# Deparse a subroutine in a data structure
perl -MData::Dumper -le '$ref=sub{print "in sub"}; &$ref; my $d=Data::Dumper->new([$ref])->Deparse(1); print $d->Dump'
# Deparse/show the code of a subroutine
perl -MData::Dumper -le '$Data::Dumper::Deparse=1; sub add{my($a,$b)=@_; $a+$b}; print Dumper \&add'
perl -MData::Dumper -le '$Data::Dumper::Deparse=1; $add=sub{my($a,$b)=@_; $a+$b}; print Dumper $add'
# Data Dumper subroutine template
sub _dumper {
require Data::Dumper;
my $data = Data::Dumper
->new( [@_] )
->Indent( 1 )
->Sortkeys( 1 )
->Terse( 1 )
->Useqq( 1 )
->Dump;
return $data if defined wantarray;
say $data;
}
#############################################################
## Perl Modules - Data::Printer
#############################################################
# Colorful data dumper.
# p - print.
# np - capture dump output.
perl -MData::Printer -E 'my $var = [1..3, {a => 1, b => 2}, 123]; p $var'
[
[0] 1,
[1] 2,
[2] 3,
[3] {
a 1,
b 2
},
[4] 123
]
#############################################################
## Perl Modules - Data::Trace
#############################################################
# Show where a complex data structure is being updated.
cpanm Data::Trace
perl -MData::Trace -Mojo -E 'my $data = {a => [0, {complex => 1}]}; say "\nBefore:"; say r $data; Data::Trace->Trace($data); sub BadCall{ $data->{a}[0] = 1 } say ""; BadCall(); say "After:"; say r $data'
# Data::Trace (WIP).
perl -Me -MData::Trace -E 'get("Kernel::System::Cache")->Set( Type => "Ticket", Key => "ABC", Value => [1..3] ); Data::Trace->Trace( get("Kernel::System::Cache") ); get("Kernel::System::Cache")->Delete( Type => "Ticket", Key => "ABC" )'
#############################################################
## Perl Modules - DBD::mysql
#############################################################
# Bug in DBD::mysql before version 5.007:
#
cpanm DBD::mysql@5.006
perl -Me2 -e '$d = get("Kernel::System::DB"); $d->Connect; $d->Disconnect; $d->Connect; say "END"'
ConnectCached
Disconnect
ConnectCached
Segmentation fault (core dumped)
#
cpanm DBD::mysql@5.007
perl -Me2 -e '$d = get("Kernel::System::DB"); $d->Connect; $d->Disconnect; $d->Connect; say "END"'
ConnectCached
Disconnect
ConnectCached
END
#############################################################
## Perl Modules - DBI
#############################################################
# How to connect to database using perl DBI (postgres,sample,sql)
perl -MDBI -E '$dbh = DBI->connect("DBI:Pg:dbname=$db; host=127.0.0.1", "$user", "$pass", {RaiseError => 1}) or die $DBI::errstr; say "\nOpened db successfully!\n"'
# How to query information from a database using perl (postgres,sample,sql)
perl -MDBI -E 'sub Die { die $DBI::errstr } $dbh = DBI->connect("DBI:Pg:$db=srto_8_0; host=127.0.0.1", "$user", "$pass", {RaiseError => 1}) or Die; $sth = $dbh->prepare(q(SELECT * from MyTable;)) or Die; $sth->execute() or Die; while(@row = $sth->fet...
# Fetchbdata from SQLite database.
perl -MDBI -E 'my $dbh = DBI->connect("DBI:SQLite:kjv.bbl.mybible", '', '', {RaiseError => 1}); my $sth = $dbh->prepare("select * from Bible limit 3"); $sth->execute; while(my @row = $sth->fetchrow_array ){ say "@row" } $dbh->disconnect'
perl -MDBI -E 'my $dbh = DBI->connect("DBI:SQLite:kjv.bbl.mybible", '', '', {RaiseError => 1}); my $all = $dbh->selectall_arrayref("select * from Bible limit 3"); for my $row ( @$all ){ say "@$row" } $dbh->disconnect'
perl -MDBI -E 'my $dbh = DBI->connect("DBI:SQLite:kjv.bbl.mybible", '', '', {RaiseError => 1}); for my $row ( $dbh->selectall_array("select * from Bible limit 3") ){ say "@$row" } $dbh->disconnect'
# View install drivers for DBI.
perl -MDBI -E 'say for DBI::available_drivers'
# Example using selectrow_hashref.
perl -MData::Printer -MDBI -E 'my $t=shift; my $d = DBI->connect("DBI:SQLite:$t"); my $r = $d->selectrow_hashref("select * from details"); p $r' $t
#############################################################
## Perl Modules - DBI::Profile
#############################################################
# Profile SQL statements in perl DBI.
# Install and export.
cpanm DBI::Profile
export DBI_PROFILE='!Statement'
#
# Report explicitly (instead of on DESTROY)
## Perl Modules - Devel::REPL
#############################################################
# Using a read,evaluate,print,loop in perl.
perl -MDevel::REPL -E '
my $my_var = 111;
our $our_var = 222;
my $repl = Devel::REPL->new;
$repl->load_plugin($_) for qw(
History
LexEnv
DDS
Colors
Completion
CompletionDriver::INC
CompletionDriver::LexEnv
CompletionDriver::Keywords
CompletionDriver::Methods
);
$repl->run;
'
#############################################################
## Perl Modules - Devel::Size
#############################################################
# Find out the size of variables.
use Devel::Size qw( total_size );
say "size: " . total_size($bytes);
#############################################################
## Perl Modules - Email::Address::XS
#############################################################
# Example of using Email::Address::XS
perl -Mojo -MEmail::Address::XS -E 'say r $_ for Email::Address::XS->parse("First Last email\@localhost")'
bless( {
"comment" => undef,
"host" => undef,
"invalid" => 1,
"original" => "First ",
"phrase" => undef,
"user" => "First"
}, 'Email::Address::XS' )
#############################################################
## Perl Modules - Email::Outlook::Message
#############################################################
# Parse an outlook message .msg file
perl -MEmail::Outlook::Message -le 'print Email::Outlook::Message->new(shift)->to_email_mime->as_string' "$m"
#############################################################
## Perl Modules - Enbugger
#############################################################
# Using a read,evaluate,print,loop in perl.
# Not updated since 2014 and failing to build.
#############################################################
## Perl Modules - Encode
#############################################################
# Example of using Encode to show string in different supported encodings (broken).
perl -C -MEncode -E '$s1="Ue: Ü"; $s2="Euro: \N{EURO SIGN}"; for ( encodings ) { printf "%-15s: [%-7s] [%s]\n", $_, encode($_,$s1), encode($_,$s2) }'
# Why use Encode?
perl -E 'say "\xe1"' # �
perl -C -E 'say "\xe1"' # á
perl -MEncode -E 'say encode "UTF-8", "\xe1"' # á
perl -MEncode -E 'use open ":std", ":encoding(UTF-8)"; say "\xe1"' # á
perl -MEncode -E 'use open qw(:std :utf8); say "\xe1"' # á
# Mixed up encoding.
perl -MEncode -E '$s = encode("UTF-8","é", Encode::FB_CROAK|Encode::LEAVE_SRC); say length($s) . " $s"'
4 é
perl -C -MEncode -E '$s = encode("UTF-8","é", Encode::FB_CROAK|Encode::LEAVE_SRC); say length($s) . " $s"'
4 é
perl -Mutf8 -MEncode -E '$s = encode("UTF-8","é", Encode::FB_CROAK|Encode::LEAVE_SRC); say length($s) . " $s"'
2 é
perl -C -Mutf8 -MEncode -E '$s = encode("UTF-8","é", Encode::FB_CROAK|Encode::LEAVE_SRC); say length($s) . " $s"'
2 é
# Decoding example.
perl -C -MEncode -E 'say decode("UTF-8", chr(0xc3).chr(0xa9), Encode::FB_CROAK)'
é
#############################################################
## Perl Modules - Excel::Writer::XLSX
#############################################################
# Excel - Simple: Generate a blank xlsx file
perl -MExcel::Writer::XLSX -E "$wb = Excel::Writer::XLSX->new('my.xlsx'); $wb->close"
# Excel - Simple: Check for errors openning an excel file and write to a cell
# Also rename the worksheet
perl -MExcel::Writer::XLSX -E "$wb = Excel::Writer::XLSX->new('my.xlsx') or die qq($!\n); $ws = $wb->add_worksheet('my'); $ws->write('A1', 'Hello Excel'); $wb->close"
# Excel - Simple: Add a format to make a cell bold
perl -MExcel::Writer::XLSX -E "$wb = Excel::Writer::XLSX->new('my.xlsx') or die qq($!\n); $ws = $wb->add_worksheet('my'); $format = $wb->add_format; $format->set_bold; $ws->write(0, 0, 'Hello Excel', $format); $wb->close"
# Create a spreadsheet/excel with formulas using perl (only on lnxbr42)
perl -MExcel::Writer::XLSX -le '
$wb=Excel::Writer::XLSX->new("new.xlsx");
$ws=$wb->add_worksheet;
$ws->write("A1","In Excel");
$ws->write("B2",3);
$ws->write("B3",4);
$ws->write("B4","=B2+B3");
$ws->write("B5","=SUM(B2:B4)");
$wb->close
'
# Create a spreadsheet/excel with color formats using perl (only on lnxbr42)
perl -MExcel::Writer::XLSX -le '
$wb=Excel::Writer::XLSX->new("new2.xlsx");
# Perl Modules - Text::ParseWords example.
sub get_file_data{
use Text::ParseWords;
map{chomp; [quotewords('\s+', 1, $_)]} <DATA>;
}
#############################################################
## Perl Modules - Tie::Array
#############################################################
# Tie a simple array variable
perl -MData::Dumper -MTie::Array -le 'tie @a, "Tie::StdArray"; @a=(1,3,4); print Dumper tied @a'
#############################################################
## Perl Modules - Tie::File
#############################################################
# Tie an array to a file
perl -MTie::File -le 'tie @file,"Tie::File","array.pl"; print $file[4]'
#############################################################
## Perl Modules - Tie::Hash
#############################################################
# Tie a simple hash variable
perl -MData::Dumper -MTie::Hash -le 'tie %h, "Tie::StdHash"; $h{age}=123; print Dumper tied %h'
# Tie append hash example.
package Tie::AppendHash;
use Tie::Hash;
our @ISA = qw(Tie::StdHash);
sub STORE {
my ($self, $key, $value) = @_;
push @{$self->{$key}}, $value;
}
#############################################################
## Perl Modules - Tie::Scalar
#############################################################
# Tie a simple scalar variable
perl -MData::Dumper -MTie::Scalar -le 'tie $n, "Tie::StdScalar"; $n=5; print Dumper tied $n'
perl -Me -MTie::Scalar -e 'my $obj = tie $var, "Tie::StdScalar"; $var=5; p $var; p $obj'
# Tie to scalar (without template)
perl -le '{package P; sub TIESCALAR{my($c,$o)=@_; bless \$o,$c} sub FETCH{my($s)=@_; $$s} sub STORE{my($s,$v)=@_; $$s = $v} } tie $var, "P", 123; print $var; $var=42; print $var'
#############################################################
## Perl Modules - Tie::Watch
#############################################################
# Tie Watch. OOP interface that hides making packages for tied variables
perl -MTie::Watch -le 'my $v=1; Tie::Watch->new(-variable => \$v, -fetch => sub{my $s=shift; $v=$s->Fetch; $s->Store($v+1); $v}); print $v; print $v; print $v'
# Check when a variable is updated. (watcher)
perl -MTie::Watch -Mojo -le 'my $h={a => [1..2]}; say r $h; Tie::Watch->new( -variable => \$h->{a}, -store => sub{my ($s,$v) = @_; $s->Store($v); my $Scope = 0; while( my ($Pkg,$Line) = caller(++$Scope) ){ say "$Pkg:$Line" } }); sub func{$h->{a}=456}...
# Check when a variable is updated. (watcher)
use Tie::Watch;
Tie::Watch->new(
-variable => \$Self->{Cache}->{ $Param{Type} }->{ $Param{Key} },
-store => sub{
my ($S,$Value) = @_;
$S->Store($Value);
my $Scope = 0;
my $Limit = 5;
while( my ($Package,$Line) = (caller(++$Scope))[0,2] ){
next if $Package =~ /\ATie::/;
say "* Store: $Package line $Line";
last if $Scope >= $Limit;
}
},
);
# Problem using Tie::Watch with Storable::dclone.
perl -MData::Tie::Watch -MStorable -e '$data = {}; $obj = Data::Tie::Watch->new( -variable => $data ); Storable::dclone($data)'
perl -MData::Tie::Watch -MStorable -e '$data = 111; $obj = Data::Tie::Watch->new( -variable => \$data ); Storable::dclone(\$data)'
Can't store CODE items at -e line 1.
# Sample test code.
perl -Me -Ilib -MData::Tie::Watch -e '{ my $data = []; Data::Tie::Watch->new( -variable => $data ); my $d2 = {}; Data::Tie::Watch->new( -variable => $d2 ); } say "DONE"'
perl -Me -Ilib -MData::Trace -e '{ my $d1 = []; my $d2 = {}; Trace($d1); Trace($d2); $d1->[2] = 22; $d2->{cat} = 1 } say "DONE"; use Data::Tie::Watch; p \%Data::Tie::Watch::METHODS'
#############################################################
## Perl Modules - Time::HiRes
#############################################################
# Perl Modules - Time::HiRes
# Higher resolution sleeps.
perl -MTime::HiRes=sleep -E 'sleep 0.25 and say "sleeping" while 1'
#############################################################
## Perl Modules - Time::Moment
#############################################################
# Difference between with_offset_same_instant and with_offset_same_local.
# Instant form will use the time zone from the object (Probably what you want).
perl -MTime::Moment -E '$tm = Time::Moment->now; $tmi = $tm->with_offset_same_instant(0); $tml = $tm->with_offset_same_local(0); say "Normal: $tm"; say "Instance: $tmi"; say "Local: $tml"'
# Normal: 2022-03-10T18:44:46.882016+01:00
# Instance: 2022-03-10T17:44:46.882016Z
# Local: 2022-03-10T18:44:46.882016Z
# Timestamp using milliseconds.
perl -MTime::Moment -E 'say Time::Moment->now->strftime("%Y/%m/%d-%T%3f")'
#############################################################
## Perl Modules - Time::Piece
#############################################################
# Prefer using Time::Piece over DateTime if possible
#
# 1. Less dependencies:
cpanm --showdeps Time::Piece -q | wc -l # 4
cpanm --showdeps DateTime -q | wc -l # 35
#
( run in 2.179 seconds using v1.01-cache-2.11-cpan-8f98c5d2c55 )