Author:
erics, April 16th, 2021
The key is to define a variable first, then use the BEGIN block to initialize the variable, then reference the variable in use lib $var; later on ;-} For example, enable a module contained in the same directory as a script called via the PATH:
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#!/ussr/bin/env perl use strict; use warnings; our $scriptPath; BEGIN { eval { use File::Basename; use File::Spec; $scriptPath = dirname(File::Spec->rel2abs(__FILE__)); 1; } or do { die "$0 use CRASHED: $@"; }; } use lib $scriptPath; eval { use MyModule::ABC; 1; } or do { die "$0 use CRASHED: $@"; }; |
Categories: How-To's, Technology Tags: @INC, compile, Compile-time, Dir, directory, howto, include, lib, Library, module, Path, perl, require, Run-time, runtime, tips, Use, use lib
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Author:
erics, March 9th, 2021
The trick to using eval to catch shell execution is to return twice, once inside the eval and once outside:
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sub isMaintenance { my $return = eval { my $err=system("check_policy.sh | grep 'Policy is MAINTENANCE' >/dev/null 2>/dev/null"); &debug("perl error code: $err"); $err=$err / 256; &debug("system error code: $err"); if ($err != 0) { # Not Maintenance if ($verbose) { warn "policy is NOT MAINTENANCE\n"; } return 0; } else { return 1; } }; return $return; } |
Neat!
Categories: How-To's, Technology Tags: Code, eval, Exit, Exit Code, howto, perl, Return, System
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Author:
erics, February 11th, 2021
## to add a single backslash in front of whatever char was matched
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my $password = q#abc'A1r%Fgt&jh[-#; $password =~ s/(['])/\\$1/g; print qq#'$password'\n#; 'abc\'A1r%Fgt&jh[-' |
## to double whatever char was matched
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my $password = q#abc'A1r%Fgt&jh[-#; $password =~ s/(['])/$1$1/g; print qq#'$password'\n#; 'abc''A1r%Fgt&jh[-' |
## to convert ‘ to ‘\” for shell execution
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my $password = q#abc'A1r%Fgt&jh[-#; $passwordShell =~ s/(['])/$1\\$1$1/g; print qq#'$password'\n#; 'abc'\''A1r%Fgt&jh[-' |
Categories: How-To's, Technology Tags: Backslash, Characters, double, double quotes, Escape, howto, perl, quote, quotes, Replace, Single, single quotes, Speci, Special, Special character, Substitute, tips
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Author:
erics, December 3rd, 2020
Problem While running the aws cli command from a Perl async command inside apid, I go the following error:
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IOError: [Errno 10] No child processes |
Solution The issue turned out to be a bug in Python2.7, so I upgraded to Python3.4, then uninstalled and re-installed the aws cli software so that it used the proper Python34 version. Procedure
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sudo -i cd ## Upgrade Python yum install python34 alternatives --config python ## "Uninstall" old aws cli mv /opt/aws /opt/aws.fcs cd /usr/bin/ mv aws aws.fcs mv aws_completer aws_completer.fcs ## Install new aws cli curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip" -o "awscliv2.zip" unzip awscliv2.zip ./aws/install -i /opt/aws -b /usr/bin /usr/bin/aws --version |
https://docs.aws.amazon.com/cli/latest/userguide/install-cliv2-linux.html […]
Categories: How-To's, Technology Tags: alternatives, API, apid, AWS, aws cli, AWS Linux, Broken, cli, Cloudformation, Command, Curl, Error, Exec, Execute, howto, IOError, Linux, No child processes, perl, Python, Python27, Python34, tips, Yum
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Author:
erics, July 8th, 2020
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my $stamp = strftime "%Y%m%d%H%M%S", gmtime time; ## in-place update for the file our $^I = ".$stamp"; local @ARGV = ($fullpath); while ( <ARGV> ) { if (/$regex/) { next; } # this print is the critical part to write the line back to the file print; } $^I = undef; |
Categories: How-To's, Technology Tags: Change, Edit, Edit In Place, howto, in place, Inline, modify, perl, Place, Script, tips
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Author:
erics, July 8th, 2020
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use POSIX qw(strftime); my $stamp = strftime "%Y%m%d%H%M%S", localtime; my $stamp = strftime "%Y%m%d%H%M%S", gmtime; |
Categories: How-To's, Technology Tags: Date, datetime, gmtime, howto, localtime, perl, Stamp, strftime, time, timedate, Timestamp, tips
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Author:
erics, March 23rd, 2020
Using PERL, we can easily do a search and replace across multiple files. perl -ni -w -e ‘print unless m/^gdb\d+/;’ yourFileSpec
Categories: How-To's, Technology Tags: Batch, Delete, Edit, Edit In Place, howto, in place, perl, search, tips
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Author:
erics, December 11th, 2019
When using Perl’s exec() call, the best way to invoke it is as follows:
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exec("$dir/myprog.sh",@ARGV); |
This syntax does some important things: – passes a scalar value as the first argument which exec interprets as PROGRAM – passes an array as the second argument which exec will use as the arguments to pass into PROGRAM Note […]
Categories: How-To's, Technology Tags: Arg, Args, Argument, Arguments, bash, Exec, Execute, perl, Program, sh, Shell, System
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Author:
erics, October 9th, 2019
Use Case: Export Apple Reminders from MacOS application to cleaned plain text, i.e. remove unwanted spaces, blank lines and square brackets PROCEDURE Click on a single item in the MacOS Reminders app list Select All (either Command-a or use Edit->Select All) Copy (either Command-c or use Edit->Copy) Open Terminal Run cleanme Paste the copied reminders […]
Categories: How-To's, Technology Tags: apple, array, input, List, MacOS, Multi, Multi-line, Multiline, Multiple, perl, Plain, Plaintext, Read, Reminders, STDIN, Terminal, text()
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Author:
erics, August 4th, 2019
I wanted to call a sub-routine based on a variable in Perl, like this:
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our $role = 'master'; &$role; |
but it failed because of use strict:
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Can't use string ("master") as a subroutine ref while "strict refs" in use at /opt/continuent/tungsten/tools/tungsten_find_orphaned line 213. |
To enable using a variable as a reference, simply specify that to Perl:
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use strict no strict "refs"; |
Categories: How-To's, Technology Tags: de-reference, dereference, howto, no strict, perl, Reference, Strict, Subroutine, tips, Variable
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