Log
Log may refer to:
- '''Log''' (disambiguation), a list of meanings of the term
** [[Log (wood)|Log (wood)]], a portion of the trunk or stem of a tree
** [[Log (unit of volume)|Log (unit of volume)]], a unit of measure for timber
- In [[mathematics]]:
** [[Logarithm]], the inverse function to exponentiation
** [[Binary logarithm]], logarithm with base 2
- In [[computing]]:
** [[Log file]], a file that lists actions by software
** [[Logging (computing)|Logging (computing)]], the act of keeping a log
- In [[nautical]] contexts:
** [[Chip log]], a maritime device for measuring speed
** [[Logbook]], a record of events
- In [[Arts, Entertainment, and Media]]:
** [[Publications titled Log]], various works
** [[Audio-visual works titled Log]], various works
- '''Log, Croatia''', a village
- '''Log, West Virginia''', an unincorporated community
Forestry and Materials
Log (wood)
A log in the context of wood is defined as a bulky piece or length of a cut or fallen tree, particularly a segment of the trunk ready for sawing, typically over six feet (1.8 meters) long.[1] These logs are harvested from felled trees in forestry operations and prepared for various applications, serving as the primary raw material in wood-based industries.
Historically, logs have been essential for construction, such as in building log cabins, which originated in Nordic and Eastern European traditions dating back to the Bronze Age around 3500 BC, with straight, tall trees in regions like Fennoscandia facilitating the notching and stacking technique.[2] In North America, Swedish and Finnish settlers introduced log cabins around 1640 in the Delaware River valley, using them for durable frontier housing.[3] Logs were also crafted into furniture, with rustic log furniture emerging among 18th-century European settlers in the United States for its pioneer aesthetic and use of whole logs.[4] As firewood, logs fueled hearths, exemplified by the Yule log tradition from ancient Nordic pagan winter solstice celebrations, where a large log was burned over several days for warmth and ritual protection.[5]
In modern industry, logs are processed by debarking and sawing into lumber for construction and other uses, or chipped and pulped for paper production, where wood fibers are isolated through chemical or mechanical means in mills.[6] Global timber production reached approximately 4 billion cubic meters annually as of recent FAO assessments, though harvesting contributes to environmental impacts like habitat fragmentation and biodiversity loss, affecting up to 10% of global greenhouse gas emissions from deforestation.[7][8]
Logs are categorized into softwood and hardwood types based on tree species. Softwoods, from coniferous trees like pine, grow faster and have lower density, making them suitable for construction lumber due to their straight grain and ease of processing.[9] Hardwoods, from deciduous trees like oak, are denser and slower-growing, prized for furniture owing to their strength and durability.[9]
Handling logs requires caution due to their substantial weight; for instance, a 10-foot pine log with a 10- to 14-inch diameter typically weighs 200-380 pounds, varying by moisture content and species.[10] Logging accidents commonly result in injuries from falling objects like trees or logs, which account for about 33% of incidents, alongside strains, slips, and equipment contact, with the industry reporting over 8,000 nonfatal injuries requiring time off work annually in the U.S. from 2006-2015.[11][12]
Log (unit of volume)
The log (Hebrew: לוג, lōḡ) was an ancient unit of liquid volume in the Hebrew Bible, primarily used for measuring oil, wine, and dry goods such as flour in ritual contexts. It represented the smallest standard liquid measure, equivalent to one-twelfth of a hin and approximately one-quarter of a cab (qab). Scholarly estimates place its capacity at approximately 0.3 to 0.6 liters, with variations between biblical and Talmudic standards; for instance, some Talmudic metrology suggests about 0.545 liters based on Roman sextarius equivalence and vessel analyses. In post-biblical Jewish tradition, the log was often equated to the Roman sextarius for practical purposes.[13][14][15]
Originating from ancient Near Eastern measurement systems, the log appears in biblical texts such as Leviticus 14:10–24, which prescribes its use in offerings (e.g., one log of oil for purification rites), and Ezekiel 45:14, referencing proportions of oil tithes. It derives from broader regional practices, with archaeological evidence linking it to Ugaritic "lg" measures around 1500 BCE and similar Egyptian liquid units from the Late Bronze Age, indicating a shared metrological tradition across Palestine, Syria, and Egypt. The hin, as a parent unit, was standardized in these cultures for cultic and trade purposes, with the log serving as a fractional subdivision.[15][16][17]
In Jewish law (Halakha), the log held significance for tithes, temple offerings, and purity rituals, with its exact subdivisions debated in Talmudic literature; for example, the Mishnah and Babylonian Talmud equate one log to four revi'it (quarters), influencing calculations for minimal portions in religious observances. These texts, such as in tractate Keritot, discuss conversions to ensure compliance with scriptural mandates, though discrepancies arose between Judean and Babylonian measures. By the Roman era, the log fell into obsolescence, supplanted by Greco-Roman and later metric systems, surviving only in scholarly reconstructions and religious studies without contemporary practical revival.[18][14]
Mathematics
Logarithm
In mathematics, the logarithm of a positive real number x to a base b > 0, b \neq 1, is defined as the exponent y to which b must be raised to obtain x, satisfying b^y = x and denoted \log_b x = y.[19] This inverse relationship to exponentiation transforms multiplicative operations into additive ones, facilitating complex calculations. The concept originated with Scottish mathematician John Napier, who published the first table of logarithms in 1614 in Mirifici Logarithmorum Canonis Descriptio to simplify astronomical and trigonometric computations by converting products to sums.[20] English mathematician Henry Briggs refined Napier's work by proposing base-10 logarithms, known as common logarithms, which he detailed in tables published in 1624, making them practical for decimal-based arithmetic.[21] In the 18th century, Leonhard Euler introduced the base e \approx 2.71828 and used the notation \log x for the natural logarithm, linking it to the exponential function \exp x = e^x. The notation \ln x was introduced later by Irving Stringham in 1893.[20][22]
Logarithms exhibit several fundamental properties that underpin their utility. The product rule states \log_b(xy) = \log_b x + \log_b y for x, y > 0, allowing multiplication to be reduced to addition.[23] Similarly, the quotient rule gives \log_b(x/y) = \log_b x - \log_b y, and the power rule yields \log_b(x^n) = n \log_b x for real n.[23] The change-of-base formula, \log_b x = \log_k x / \log_k b for any valid base k > 0, k \neq 1, enables conversion between different logarithmic systems.[23] These properties hold for the principal branch of the logarithm in the complex plane but apply directly to positive real arguments in elementary contexts. Common logarithms (\log_{10}) are widely used in engineering and science; for instance, \log_{10} 100 = 2 since $10^2 = 100.[23] Natural logarithms satisfy \ln e = 1, reflecting the base's definition as the limit \lim_{n \to \infty} (1 + 1/n)^n.[19]
Logarithms are indispensable for solving exponential equations and modeling natural phenomena. For example, to solve $2^x = 8, take the base-2 logarithm: x = \log_2 8 = 3, as $2^3 = 8.[19] In population dynamics, the exponential growth model dP/dt = kP integrates to P(t) = P_0 e^{kt}, where solving for time t requires t = \frac{1}{k} \ln(P / P_0), illustrating logarithms' role in deriving time from observed growth.[24] Computationally, logarithms are approximated using series expansions; the Taylor series for the natural logarithm is \ln(1 + x) = x - \frac{x^2}{2} + \frac{x^3}{3} - \frac{x^4}{4} + \cdots for |x| < 1, derived by integrating the geometric series for $1/(1 + x).[25] A specialized variant, the binary logarithm with base 2, finds application in computing for analyzing algorithm efficiencies.[19]
Binary logarithm
The binary logarithm, denoted as \log_2 x, is the exponent to which 2 must be raised to obtain x, for x > 0.[26] For example, \log_2 8 = 3 because $2^3 = 8.[26]
A distinctive property of the binary logarithm is that it yields integer values for powers of 2, such as \log_2(2^k) = k for nonnegative integer k.[26] In computing, it relates directly to binary representation: the minimum number of bits required to represent a positive integer n is \lfloor \log_2 n \rfloor + 1, as this counts the positions from the most significant bit to the least.[27]
The binary logarithm gained prominence in computing through Claude Shannon's 1948 work on information theory, where it measures uncertainty in bits.[28] Shannon defined the entropy H of a discrete random variable with probabilities p_i as H = -\sum p_i \log_2 p_i, quantifying information in binary digits (bits).[29]
In algorithm analysis, the binary logarithm appears in time complexities for divide-and-conquer methods, such as binary search, which runs in O(\log_2 n) time on a sorted array of n elements by halving the search space iteratively.[30] For balanced binary trees with n nodes, the height is \log_2(n+1), reflecting the logarithmic growth in levels for efficient traversal.[31]
In digital signal processing, the binary logarithm determines the number of stages in radix-2 fast Fourier transform (FFT) algorithms, which compute the discrete Fourier transform in O(n \log_2 n) time for n points by recursively dividing into even and odd indices.[32]
The binary logarithm relates to the common (base-10) logarithm via the change-of-base formula: \log_2 x = \log_{10} x / \log_{10} 2 \approx \log_{10} x / 0.3010.[33]
In modern quantum computing, the binary logarithm specifies the number of qubits needed for a Hilbert space of dimension d, as n = \log_2 d for d = 2^n, enabling representation of quantum states in exponentially large spaces.[34] In AI, transformer models often scale complexity with \log n in variants like logarithmic-depth architectures, allowing efficient processing of sequences up to length n while approximating full attention.[35]
Computing and Technology
Log file
A log file is a computer-generated, timestamped record of events and activities occurring within a computing system, including software operations, hardware interactions, errors, user actions, and transactions. These files serve as chronological documentation to facilitate debugging, performance monitoring, auditing, and security analysis in operating systems, applications, and networks.[36][37]
Log files have been used since the early days of computing for tracking operations, with practices emerging in the 1960s alongside mainframe systems for debugging and auditing. In Unix-like systems, logging facilities were introduced in the 1970s, such as the login command in Version 6 Unix (1975), which recorded user sessions to the wtmp file; by the 1980s, the /var/log directory became a standard location for log storage in Unix variants.[38][39][40]
Log files employ various formats to structure their data for readability and parsing. Plain text formats are common in traditional systems, such as the Apache HTTP server's access.log, which uses the Common Log Format to capture fields like client IP address, request timestamp, HTTP request details, status code, and bytes transferred. For example, a typical entry might appear as:
127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326
127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326
Modern applications often use structured formats like JSON for easier machine parsing, embedding key-value pairs for elements such as timestamps, log levels, and event descriptions. The syslog protocol, standardized in RFC 5424 (published 2009), provides a transport-independent format for event notifications, consisting of a header (including priority, version, timestamp, hostname, application name, process ID, and message ID), optional structured data (e.g., key-value pairs for metadata like origin or quality), and a free-form UTF-8 message body. This format supports layered transmission over UDP or TLS, with implementations recommended to support messages up to 2048 octets.[41][42]
Common types of log files include system logs, which record kernel-level events such as hardware failures or process startups (e.g., /var/log/messages in Linux); application logs, which detail software-specific activities like web server 404 errors or database queries; and security logs, which track authentication attempts, including failed logins or access denials to detect potential intrusions. These categories enable targeted analysis, with system logs focusing on OS stability, application logs on program behavior, and security logs on compliance and threat detection.[37][43]
Due to continuous event logging, files can expand rapidly to gigabytes in high-volume environments like busy servers, risking disk space exhaustion and performance degradation. Management practices involve rotation utilities such as logrotate, a standard Linux tool that automates archiving, compression (e.g., via gzip), and deletion of old logs based on criteria like size, age, or frequency—typically configured to rotate daily or when exceeding a threshold like 100 MB, retaining a set number of archives (e.g., four weeks' worth). For advanced parsing and analysis, tools like grep enable simple text searches, while the ELK Stack—comprising Elasticsearch for searchable storage, Logstash for data processing and ingestion, and Kibana for visualization—facilitates centralized querying and alerting across distributed systems.[44][45]
Privacy and security considerations are critical, as log files often contain sensitive information like IP addresses or user identifiers. Regulations such as the EU's General Data Protection Regulation (GDPR), effective since 2018 and applicable in 2025, mandate anonymization or pseudonymization of personal data in logs to prevent re-identification, treating fully anonymized data as outside GDPR scope while requiring strict controls (e.g., encryption and access limits) for pseudonymized entries. Security risks include log injection attacks, where attackers insert malicious payloads via unvalidated input to forge entries, evade detection, or disrupt monitoring—mitigated by input sanitization and adherence to standards like OWASP guidelines.[46][47]
Logging (computing)
Logging in computing refers to the systematic recording of events, states, errors, or other relevant data generated by software applications, operating systems, or hardware components during their operation, primarily for purposes such as monitoring, debugging, auditing, and performance analysis. This practice enables developers, system administrators, and security teams to reconstruct past activities, diagnose issues, and ensure compliance with regulatory standards. Unlike simple output statements, logging is designed to be configurable, structured, and persistent, often directing records to files, databases, or remote services for long-term retention and querying.)[48]
A key aspect of logging is the use of severity levels to categorize events based on their importance, allowing filtering and prioritization during analysis. Common levels include DEBUG for detailed diagnostic information, INFO for general operational messages, WARN for potential issues that do not halt execution, ERROR for failures that affect functionality, and FATAL for critical errors that terminate the process. These levels are standardized in many frameworks, such as Python's built-in logging module, which supports levels from 10 (DEBUG) to 50 (CRITICAL, akin to FATAL), enabling fine-grained control over what gets recorded in different environments.[49] Similarly, Java's Log4j library implements these levels, though it gained notoriety due to the Log4Shell vulnerability (CVE-2021-44228) in December 2021, which allowed remote code execution via malicious log messages and affected millions of systems worldwide.[50]
Implementation of logging typically involves integrating dedicated libraries or modules into code, with configuration files specifying output destinations, formats, and filters. For example, in pseudocode, a developer might use:
import [logging](/page/Logging)
logger = [logging](/page/Logging).getLogger(__name__)
logger.setLevel([logging](/page/Logging).INFO)
# Configure handler to output to file or console
handler = [logging](/page/Logging).FileHandler('app.log')
formatter = [logging](/page/Logging).Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler.setFormatter(formatter)
logger.addHandler(handler)
# Log an event
logger.info("User logged in: %s", user_id)
import [logging](/page/Logging)
logger = [logging](/page/Logging).getLogger(__name__)
logger.setLevel([logging](/page/Logging).INFO)
# Configure handler to output to file or console
handler = [logging](/page/Logging).FileHandler('app.log')
formatter = [logging](/page/Logging).Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
handler.setFormatter(formatter)
logger.addHandler(handler)
# Log an event
logger.info("User logged in: %s", user_id)
This approach supports rotation policies to manage file sizes and asynchronous modes to minimize performance impact. Outputs can be directed to consoles for immediate feedback, files for persistence, or cloud services like AWS CloudWatch for scalable aggregation.[51]
Best practices emphasize structured logging, where events are recorded in machine-readable formats like JSON rather than plain text, facilitating parsing and querying in tools. Including correlation IDs—unique identifiers propagated across distributed services—enables tracing requests through microservices architectures, improving root-cause analysis in complex systems. For regulated industries, logging must align with standards such as PCI-DSS Requirement 10, which mandates recording access to cardholder data, including user identities, event types, and timestamps, with logs retained for at least one year.[52][53]
Prominent tools in the logging ecosystem include Splunk for advanced search, visualization, and alerting on log data across on-premises and cloud environments, and Fluentd as an open-source data collector that unifies ingestion from multiple sources into centralized storage.[54][55] As of 2025, trends highlight AI-driven anomaly detection, where machine learning models analyze log patterns to identify deviations indicative of security threats or failures, with adoption growing in IT operations due to integrations in platforms like Elastic Stack.[56]
Challenges in logging include performance overhead from synchronous writes, which can introduce latency in high-throughput applications; asynchronous alternatives, such as buffered queues, mitigate this by deferring I/O but risk data loss on crashes. In big data contexts, log volumes can reach petabytes daily in cloud environments, necessitating efficient compression, sampling, and distributed processing to avoid storage costs and analysis bottlenecks.
Nautical and Navigation
The chip log, also known as the common log or ship log, is a historical nautical instrument designed to estimate a vessel's speed through the water by measuring the distance traveled over a short, fixed interval. It comprises a drag device, or "chip," typically a quarter-circle or triangular piece of wood weighted with lead on its curved edge to ensure it planes steadily without rotating, attached to a calibrated line marked with knots. This method, which gave rise to the term "knot" for nautical speed (one nautical mile per hour), relied on the principle that the length of line paid out in a known time corresponds directly to the ship's velocity.[57]
The device was first systematically described in 1574 by English mathematician and gunner William Bourne in his treatise A Regiment for the Sea, marking a key advancement in practical maritime measurement. Bourne's design standardized the use of a knotted line and timed interval, building on earlier rudimentary methods like the Dutchman's log, which simply floated debris astern to gauge separation. The knots on the log-line were spaced precisely at 47 feet 3 inches (14.4 meters) apart, calibrated to align with the nautical mile (approximately 6,080 feet) when measured over 28 seconds—this interval accounted for the time to deploy the chip and ensured that one knot passing per second equated to one knot of speed. Early lines were made of tarred hemp for durability against saltwater, though later variations occasionally used wire for improved strength.[58][59]
In operation, a sailor would heave the chip overboard from the ship's stern, allowing it to trail astern as hydrodynamic drag kept it stationary relative to the water. An assistant held the line, paying it out freely from a wooden reel while another timed the run with a 28-second sandglass (a half-minute glass adjusted for deployment delay). The number of knots that passed through the hand during this period directly indicated the speed in knots; for example, five knots in 28 seconds meant five knots of speed. The chip was then hauled back aboard via a stray line, and the process repeated periodically. This manual technique demanded skill to avoid errors from line stretch, wind, or improper deployment but provided a reliable estimate for dead reckoning.[57][59]
The chip log held immense historical significance as a cornerstone of navigation during the Age of Sail, enabling mariners to compute daily runs and positions without electronic aids, long before GPS. It was indispensable on exploratory voyages, such as those of Captain James Cook in the late 18th century, where accurate speed data supported precise charting of Pacific waters. Under favorable conditions, the instrument provided sufficient accuracy for transoceanic travel despite variables like currents or hull fouling. Its simplicity made it ubiquitous on merchant and naval vessels from the 16th to 19th centuries, contributing to the expansion of global trade and exploration.[60]
By the late 17th century, the chip log's limitations—such as labor intensity and susceptibility to human error—led to its gradual replacement by mechanical alternatives, with early concepts for mechanical logs proposed by Humphrey Cole in the 1570s and practical trailed-rotor patent logs emerging in the 19th century (e.g., the 1864 taffrail log). Further advancements in the early 20th century introduced electromagnetic logs, which used induction principles to detect water flow past the hull with greater precision and less maintenance. Today, satellite-based GPS has rendered such analog tools obsolete for most commercial shipping, though the chip log persists in traditional and recreational sailing for educational or ceremonial purposes, preserving a vital link to maritime heritage.[61]
Logbook
A logbook is a chronological journal maintained to record operational events, navigational data, and significant occurrences aboard vessels or aircraft. Originating in the 17th century, ship's logbooks began as essential records for documenting position, weather conditions, and crew actions during voyages, with English examples abundant from the late 1600s preserved in archives such as the UK's National Archives in Kew.[62][63] These early logs served both practical navigation purposes and historical documentation, evolving from simple notebooks to structured formats by the end of the century on vessels like those of the Dutch East India Company.[64]
In maritime contexts, logbooks are official records mandated under the International Convention for the Safety of Life at Sea (SOLAS) of 1974, requiring ships on international voyages to maintain detailed accounts of navigational activities, incidents, drills, and pre-departure tests.[65][66] Typical entries include the ship's course, speed—often derived from traditional instruments like the chip log—weather observations, position fixes, and any unusual events such as collisions or equipment failures.[67][68] These records are signed by the officer on watch and typically reviewed and countersigned by the captain to ensure accuracy and accountability.[69]
The evolution of logbooks reflects technological advancements, transitioning from paper-based formats—such as the log of HMS Victory during the 1805 Battle of Trafalgar, which detailed key events including the death of Admiral Nelson—to electronic systems integrated with tools like the Electronic Chart Display and Information System (ECDIS), developed in the mid-1980s and standardized by the International Maritime Organization (IMO) in the 1990s. As of 2025, IMO-approved Maritime Electronic Record Books (ERBs) have become mandatory for additional vessel types, including those on cabotage lines, further digitizing record-keeping.[70][71][72][73] In aviation, flight logbooks similarly track essential data like fuel consumption, maintenance activities, and flight hours to comply with regulatory standards and support safety analyses.[74][75]
Legally, maritime logbooks hold significant weight as evidence in court proceedings related to accidents, with entries admissible if made in substantial compliance with procedural requirements under frameworks like U.S. Code Title 46.[76] The IMO provides standards for logbook formats, including guidelines in Resolution A.916(22) for bridge logs and updates for electronic versions under MARPOL conventions.[77][78] A emerging 2025 trend involves integrating blockchain technology into digital logbooks for tamper-proofing, as seen in systems like electronic oil record books where data is time-stamped and immutable to prevent alterations.[79][80]
Beyond professional use, logbooks appear in other contexts, such as the fictional "captain's log" narrative device in science fiction like Star Trek, where it serves as a storytelling tool for mission recaps.[81] Vehicle logbooks, meanwhile, record mileage for tax deductions, maintenance tracking, and expense reimbursement.[82][83]
Logbooks possess substantial archival value, with 18th-century examples in the British National Archives contributing to climate research by providing long-term weather and sea state data for reconstructing historical patterns and validating modern models.[84][85][86]
Publications titled Log
Log, an independent journal dedicated to architecture and the contemporary city, has been published three times a year by the nonprofit Anyone Corporation since its inaugural issue on September 30, 2003.[87] Founded and edited by Cynthia Davidson, who is also the executive director of Anyone Corporation, the publication emphasizes critical writing and commentary in a literary style, drawing contributions from architects, theorists, artists, and critics worldwide.[88] Its content explores interdisciplinary themes such as ecology, technology, media, and urban dynamics, often through thematic issues that address pressing contemporary challenges in the built environment.[89]
The journal's influence in academic and professional architecture communities is evident from its receipt of multiple grants from the Graham Foundation, supporting the production of various issues and highlighting its contributions to advancing architectural discourse.[90] For instance, Log 47 (Fall 2019), titled "Overcoming Carbon Form," reconceives architecture's engagement with climate change, moving beyond conventional sustainability paradigms toward broader ecological rethinking.[91] Similarly, Log 50: Model Behavior (2020) examines models not just as representational tools but as entities with inherent values and behavioral implications in architectural practice and culture.[92] By 2025, Log had produced over 60 issues, with physical copies mailed to subscribers and digital PDF editions available for purchase, ensuring accessibility in both print and online formats.[89]
Another notable publication titled Log & Timber Home Living is a bimonthly magazine focused on the design, construction, and living aspects of log, timber frame, and hybrid homes.[93] Published by Active Interest Media since the early 1980s as part of the broader log home enthusiast market, it provides practical guidance on floor plans, materials selection, energy efficiency, and interior decoration, targeting custom home builders and owners.[94] The magazine features home tours, expert advice, and supplier directories, with six issues annually distributed to readers interested in sustainable and rustic building techniques.[95] Its content prioritizes technical details like log sizing, joinery methods, and maintenance, while showcasing completed projects to inspire readers.[96]
Audio-visual works titled Log
The Yule Log is a television program that originated on WPIX in New York City in 1966, featuring a continuous loop of a fireplace with a burning yule log accompanied by holiday music. It has become a seasonal tradition, broadcast annually during the Christmas period, and has inspired similar programs on other networks, running for 2–4 hours.
In film, "The Log" (1996) is a Hong Kong crime drama directed by Jeffrey Lui, starring Michael Wong as a police officer who accidentally kills an elderly woman on New Year's Eve, leading to themes of guilt and redemption.[97] Another short film, "The Log" (2013), is an American horror piece about a couple encountering a mysterious log in the woods, directed by Kevin James Wey and noted for its suspenseful atmosphere.[98]
"The Log" (2018– ) is an American web series on YouTube following a child's adventures along the west coast of the United States with family and friends, blending travel and coming-of-age elements in short episodes.[99]
Places
Log, Croatia
Log is a small locality in the municipality of Žakanje, Karlovac County, Croatia.[100]