Latest recipes tagged "unix"

Unix tee-like functionality via a Python class (Python)

2017-03-31T14:30:30-07:00

Python recipe 580767 by Vasudev Ram (cli, command, commandline, linux, python, tee, unix, utilities, windows).

The Unix tee commmand, when used in a command pipeline, allows you to capture the output of the preceding command to a file or files, while still sending it on to standard output (stdout) for further processing via other commands in a pipeline, or to print it, etc.

This recipe shows how to implement simple tee-like functionality via a Python class. I do not aim to exactly replicate the functionality of the Unix tee, only something similar.

More details and sample output here:

https://jugad2.blogspot.in/2017/03/a-python-class-like-unix-tee-command.html

Show OS error codes and messages from the os.errno module (Python)

2017-03-01T17:18:23-08:00

Python recipe 580759 by Vasudev Ram (commandline, introspection, libraries, python, unix, utilities, windows).

This recipe is a simple Python introspection utility that displays the defined OS error codes and messages (that Python knows about) from the os.errno module. It works for both Python 2 and Python 3. For each kind of OS error defined in Python, it will display a serial number, the error code, and the corresponding error name, and English error message. E.g. the first few lines of its output are shown below:

$ py -2 os_errno_info.py

Showing error codes and names

from the os.errno module:

Python sys.version: 2.7.12

Number of error codes: 86

Idx Code Name Message

0 1 EPERM Operation not permitted

1 2 ENOENT No such file or directory

2 3 ESRCH No such process

3 4 EINTR Interrupted function call

4 5 EIO Input/output error

More information, full output and other details are available here:

https://jugad2.blogspot.in/2017/03/show-error-numbers-and-codes-from.html

A pseudo-echo, (or printf), function for any Python version. (Python)

2017-01-20T22:17:23-08:00

Python recipe 580750 by Barry Walker (amiga, apple, demo, echo, fs_uae, linux, printf, unix, windows, winuae).

A simple example of having a pseudo-echo using sys.stdout.write...

This gives exactly the same results from Python Versions, 1.4.0, 2.0.1, 2.5.6, 2.6.9, 3.4.3 and 3.5.2 on various platforms including the classic AMIGA A1200.

Enjoy finding simple solutions to often very difficult problems...

Bazza.

A utility like Unix seq (command-line), in Python (Python)

2017-01-08T17:48:57-08:00

Python recipe 580744 by Vasudev Ram (bash, command, commandline, linux, script, seq, sequence, shell, unix, utilities, utility).

This recipe shows how to create a utility like Unix seq (command-line), in Python. seq is described here:

https://en.wikipedia.org/wiki/Seq_(Unix)

but briefly, it is a command-line utility that takes 1 to 3 arguments (some being optional), the start, stop and step, and prints numbers from the start value to the stop value, on standard output. So seq has many uses in bigger commands or scripts; a common category of use is to quickly generate multiple filenames or other strings that contain numbers in them, for exhaustive testing, load testing or other purposes. A similar command called jot is found on some Unix systems.

This recipe does not try to be exactly the same in functionality as seq. It has some differences. However the core functionality of generating integer sequences is the same (but without steps other than 1 for the range).

More details and sample output are here:

https://jugad2.blogspot.in/2017/01/an-unix-seq-like-utility-in-python.html

The code is below.

A simple raw hexdumper. (Python)

2016-09-19T13:24:37-07:00

Python recipe 580697 by Barry Walker (amiga, apple, fs_uae, hex, hexdump, linux, macbook_pro, raw_hexdump, unix, windows, winuae).

This is not a hexreader. This code creates a raw hexdump of a binary file that is whitespace, optional, delimited. The dump is saved into the current directory with a ".hex" extension.

It works on just about any current platform but is designed around a stock Amiga A1200(HD) with Python 1.4.0. It also works on the current stable version 3.5.2.

I needed a hexdump some years ago for banging the Amiga hardware, and decided to modify recently for another usage but it had to still work on version 1.4.0 for the classic A1200.

Enjoy...

Text ruler for console (record-oriented data processing utility) (Python)

2016-04-17T19:32:26-07:00

Python recipe 580647 by Vasudev Ram (commandline, python, rulers, unix, utilities, windows).

This recipe shows how to create a simple text-based ruler for your command-line console. It can help you find the position of your own program's output on the line, or to find the positions and lengths of fields in fixed- or variable-length records in a text file, fields in CSV files, etc.

A binary file split utility in Python (Python)

2016-04-07T18:19:35-07:00

Python recipe 580637 by Vasudev Ram (binary, commandline, linux, python, unix, utility, windows).

This recipe shows how to create a simple binary file split utility in Python.

It takes two command line arguments: 1) the name of the input file to split , 2) the number of bytes per file into which to split the input.

File comparison utility in Python (Python)

2016-03-26T18:31:11-07:00

Python recipe 580631 by Vasudev Ram (commandline, comparison, file, files, linux, python, unix, utilities).

This is a recipe to compare any two files via a Python command-line program. It is like a basic version of the cmp command of Unix or the fc.exe (file compare) command of Windows.

Unix-like split command in Python (simple version) (Python)

2016-03-14T22:35:05-07:00

Python recipe 580620 by Vasudev Ram (commandline, linux, python, shell, split, splitting, unix, utilities, utility, windows).

This recipe shows how to create a simple version of the Unix split command in Python. The split command splits an input file into multiple smaller files, the size of each of which is specified by a command-line argument giving the number of lines per file. This is useful for multiple purposes, such as editing large files in pieces, backing up files to small capacity storage devices, sending files across the network, etc.

Python-controlled Unix pipeline to generate PDF (Python)

2016-01-07T18:02:52-08:00

Python recipe 579146 by Vasudev Ram (linux, pdf, pdf_generation, pipe, pipelining, python, python2, unix).

This recipe shows how to create a Unix pipeline that generates PDF output, under the control of a Python program. It is tested on Linux. It uses nl, a standard Linux command that adds line numbers to its input, and selpg, a custom Linux command-line utility, that selects only specified pages from its input, together in a pipeline (nl | selpg). The Python program sets up and starts that pipeline running, and then reads input from it and generates PDF output.

data_dump.py, like the Unix od (octal dump) command (Python)

2015-11-01T12:43:38-08:00

Python recipe 579120 by Vasudev Ram (data, dump, hexadecimal, linux, octal, od, representation, unix, utility, windows).

This recipe implements a simple data dump tool, roughly like the od command of Unix, which stands for octal dump (though od can also dump data in hex and other formats). This tool dumps data in character and hex formats, in this version. This is data_dump.py version 1.

Simple command-line alarm clock in Python (Python)

2015-10-25T18:27:27-07:00

Python recipe 579117 by Vasudev Ram (alarm, clock, commandline, linux, python, time, unix, windows).

This recipe shows how to create a simple alarm clock in Python, that can be run from the command line in a terminal. It lets you specify the alarm time in minutes as a command line argument, and prints a wake-up message and beeps a few times, after that time arrives. You can use 0 for the minutes to test it immediately, including to adjust the volume using your speaker controls.

A UNIX-like "which" command for Python (Python)

2015-03-20T19:23:45-07:00

Python recipe 579035 by Vasudev Ram (bash, commandline, commands, linux, shell, unix, utilities, which).

UNIX users are familiar with the which command. Given an argument called name, it checks the system PATH environment variable, to see whether that name exists (as a file) in any of the directories specified in the PATH. (The directories in the PATH are colon-separated on UNIX and semicolon-separated on Windows.)

This recipe shows how to write a minimal which command in Python. It has been tested on Windows.

Print selected text pages to PDF with Python, selpg and xtopdf on Linux (Bash)

2014-10-29T17:38:10-07:00

Bash recipe 578954 by Vasudev Ram (bash, linux, pdf, python, reportlab, shell, text, text_files, text_processing, unix).

This recipe shows how to use selpg, a Linux command-line utility written in C, together with xtopdf, a Python toolkit for PDF creation, to print only a selected range of pages from a text file, to a PDF file, for display or print purposes. The way to do this is to run the selpg utility at the Linux command line, with options specifying the start and end pages of the range, and pipe its output to the StdinToPDF.py program, which is a part of the xtopdf toolkit.

Send a message to remote syslog server (Perl)

2014-07-31T17:23:17-07:00

Perl recipe 578916 by Brett Carroll (perl, syslog, unix). Revision 2.

This script allows sending syslog messages to a remote syslog server (UNIX).

JavaScript WebSocket client for Python + Go WebSocket-based system monitoring example (JavaScript)

2014-01-03T21:09:54-08:00

JavaScript recipe 578806 by Vasudev Ram (golang, javascript, linux, python, sysadmin, unix, websockets, windows).

This recipe is the JavaScript client side of an overall recipe that shows how to do system monitoring using WebSockets, Python, Go (using websocketd), and JavaScript + HTML. The server side of the recipe (in Python, and using websocketd which is written in Go), is here:

http://code.activestate.com/recipes/578803-using-websocketd-with-python-for-web-based-system-/?in=user-4173351

The system monitoring example shows the system disk space info (total, used and free) using the Python psutil module.

Create PDF at the end of a Unix pipeline with PDFWriter (Python)

2013-12-22T22:19:00-08:00

Python recipe 578794 by Vasudev Ram (commandline, linux, pdf, pipelining, reportlab, unix, xtopdf).

This recipe shows how to create PDF output at the end of a Unix or Linux pipeline, after all the text processing required, is done by previous components of the pipeline (which can use any of the standard tools of Unix such as sed, grep, awk, etc., as well as custom programs that act as filters).

PostgreSQL database backup script (Python)

2011-07-15T08:27:05-07:00

Python recipe 577793 by Evgeniy.K (backup, linux, postgresql, python, unix).

Simple script to backup some databases from PostgreSQL on unix\linux.

Sleepsort with processes and pipes (Python)

2011-06-17T02:37:58-07:00

Python recipe 577758 by Benjamin Peterson (process, sorting, unix). Revision 2.

Sleepsort is a sorting algorithm that uses the system sleep syscall in a very creative fashion.

This is the same algorithm as recipe 577756 but using *nix processes instead of threads.

Get additional group IDs for Unix user (pwd/grp modules) (Python)

2011-06-03T02:14:18-07:00

Python recipe 577733 by realityexists (group, linux, passwd, security, unix).

The Python stdlib pwd module provides an easy way to get the primary group ID, but no way to get additional group IDs. This is a simple function that returns the additional group IDs for a given username.