PROCESS MANAGEMENT COMMANDS a Process Is an Executing Prgm

Total Page：16

File Type：pdf, Size：1020Kb

PROCESS MANAGEMENT COMMANDS A process is an executing prgm. A process is created whenever the user gives a comm. To computer and the process is given a unique number i.e. known as process ID or simply PID. In unix process communicate to each other and share the common resources like CPU, main memory & storage devices. The main process can Communicate sub-processes, known as the parent process and the child process resp. Unix provides various process management tasks like as to get info about all the running processes. Following are the commands :- 1. Ps ( process status ) Purpose :- it is used to list the running processes. Syntax :- $ps[option] options :- a-displays all processes e-displays every process running at the moment u(username)-displays processes of the single mentioned user. t(terminal name)-displays the processes running on the mentioned terminal. l-displays running processes in long format with memory related information. 2. Kill Purpose :- it sends a signal with the intention of killing one or more processes. Syntax :-$kill process-id e.g. :- $kill 4512, it will send a signal to kill process whose PID is 4512 3. Nice Purpose :- it is used with ‘&’ operator to reduce the priority of jobs. In other words, the higher the nice value ,lower is the processing priority. E.g. :- $nice -15 pwd here the ‘pwd’ command is assigned the nice value 15 4. Sleep Purpose :- it is used to suspend the execution of shell script for the specified time. Usually the time is in seconds. Syntax :- $sleep 10 this command will wait for 10 seconds before returning to the command prompt. 5. Batch Purpose :- it is used to schedule the jobs for later execution. When we submit our jobs using this comm. , Unix executes our job when it is relatively free and system load is light. In this system will assign time. E.g. :- $batch sort employee.dat/grep nagpur cntrl-d 6. At it is capable of executing Unix comm. At a future time and date. E.g. :- $at date command name>directory name/file name cntrl-d it will display date and job-id .

Copy Link

Recommended publications

The Different Unix Contexts
The different Unix contexts • User-level • Kernel “top half” - System call, page fault handler, kernel-only process, etc. • Software interrupt • Device interrupt • Timer interrupt (hardclock) • Context switch code Transitions between contexts • User ! top half: syscall, page fault • User/top half ! device/timer interrupt: hardware • Top half ! user/context switch: return • Top half ! context switch: sleep • Context switch ! user/top half Top/bottom half synchronization • Top half kernel procedures can mask interrupts int x = splhigh (); /* ... */ splx (x); • splhigh disables all interrupts, but also splnet, splbio, splsoftnet, . • Masking interrupts in hardware can be expensive - Optimistic implementation – set mask flag on splhigh, check interrupted flag on splx Kernel Synchronization • Need to relinquish CPU when waiting for events - Disk read, network packet arrival, pipe write, signal, etc. • int tsleep(void *ident, int priority, ...); - Switches to another process - ident is arbitrary pointer—e.g., buffer address - priority is priority at which to run when woken up - PCATCH, if ORed into priority, means wake up on signal - Returns 0 if awakened, or ERESTART/EINTR on signal • int wakeup(void *ident); - Awakens all processes sleeping on ident - Restores SPL a time they went to sleep (so fine to sleep at splhigh) Process scheduling • Goal: High throughput - Minimize context switches to avoid wasting CPU, TLB misses, cache misses, even page faults. • Goal: Low latency - People typing at editors want fast response - Network services can be latency-bound, not CPU-bound • BSD time quantum: 1=10 sec (since ∼1980) - Empirically longest tolerable latency - Computers now faster, but job queues also shorter Scheduling algorithms • Round-robin • Priority scheduling • Shortest process next (if you can estimate it) • Fair-Share Schedule (try to be fair at level of users, not processes) Multilevel feeedback queues (BSD) • Every runnable proc.
[Show full text]
Many Slides Borrowed from Ben Zhao, Christo Wilson, & Others
12. Network Attacks Blase Ur and David Cash (many slides borrowed from Ben Zhao, Christo Wilson, & others) February 7th, 2020 CMSC 23200 / 33250 Network threat model • Network scanning • Attacks on confidentiality (e.g., eavesdropping) • Attacks on integrity (e.g., spoofing, packet injection) • Attacks on availability (e.g., denial of service (DoS)) Scanning and observing networks Network Scanning: Ping • Essential, low-level network utility • Sends a “ping” ICMP message to a host on the internet $ ping 66.66.0.255 PING 66.66.0.255 (66.66.0.255) 56(84) bytes of data. 64 bytes from 66.66.0.255: icmp_seq=1 ttl=58 time=41.2 ms • Destination host is supposed to respond with a “pong” – Indicating that it can receive packets • By default, ping messages are 56 bytes long (+ some header bytes) – Maximum size 65535 bytes • What if you send a ping that is >65535 bytes long? Ping of Death • $ ping –s 65535 66.66.0.255 – Attack identified in 1997 – IPv6 version identified/fixed in 2013 Network Scanning: Traceroute • traceroute — hops between me and host – Sends repeated ICMP reqs w/ increasing TTL Port Scanning • What services are running on a server? Nmap • 5 seconds to scan a single machine!! SYN scan Only send SYN Responses: • SYN-ACK — port open • RST — port closed • Nothing — filtered (e.g., firewall) Port Scanning on Steroids • How do you speed up scans for all IPv4? – Don’t wait for responses; pipeline – Parallelize: divide & conquer IPv4 ranges – Randomize permutations w/o collisions • Result: the zmap tool – Scan all of IPv4 in 45mins (w/ GigE cxn) – IPv4 in 5 mins w/ 10GigE Eavesdropping Tools: Wireshark, tcpdump, Bro, … Steps: 1.
[Show full text]
Backup and Restore Cisco Prime Collaboration Provisioning
Backup and Restore Cisco Prime Collaboration Provisioning This section explains the following: • Perform Backup and Restore, page 1 • Back Up the Single-Machine Provisioning Database, page 2 • Restore the Single-Machine Provisioning Database, page 3 • Schedule Backup Using the Provisioning User Interface, page 5 Perform Backup and Restore Cisco Prime Collaboration Provisioning allows you to backup your data and restore it. You can schedule periodic backups using the Provisioning UI (Schedule Backup Using the Provisioning User Interface, on page 5). There are two backup and restore scenarios; select the set of procedures that matches your scenario: • Backup and restore on a single machine, with the same installation or a new installation. For this scenario, see Schedule Backup Using the Provisioning User Interface, on page 5. Note When backing up files, you should place the files on a different file server. Also, you should burn the backup data onto a CD. Cisco Prime Collaboration Provisioning allows you to back up system data and restore it on a different system in the event of total system failure. To restore the backup from another system, the following prerequisites must be met: • Ensure that the server to which data is restored has the same MAC address as that of the system that was backed up (the IP address and the hostname can be different). • If you are unable to assign the MAC address of the original system (the one that was backed up) to another system, contact the Engineering Team for information on a new license file (for a new MAC address). Cisco Prime Collaboration Provisioning Install and Upgrade Guide, 12.3 1 Backup and Restore Cisco Prime Collaboration Provisioning Back Up the Single-Machine Provisioning Database • The procedure to backup and restore data on a different system is the same as the procedure to backup and restore data on the same system.
[Show full text]
FIFI-LS Highlights Robert Minchin FIFI-LS Highlights
FIFI-LS Highlights Robert Minchin FIFI-LS Highlights • Nice face-on galaxies where [CII] traces star formation [CII] traces star formation in M51 Pineda et al. 2018 [CII] in NGC 6946 Bigiel et al. 2020 [CII] particularly important as H2 & SFR tracer in inter-arm regions FIFI-LS Highlights • Nice face-on galaxies where [CII] traces star formation • Galaxies where [CII] doesn’t trace star formation [CII] from shocks & turbulence in NGC 4258 • [CII] seen along X-ray/radio ‘arms’ of NGC 4258, associated with past or present jet activity • [CII] excited by shocks and turbulence associated with the jet impacting the disk • NOT star formation Appleton et al. 2018 Excess [CII] in HE 1353-1917 1011 HE 1353-1917 1% MUSE RGB Images: 0.1 % • HE 1353-1917 1010 iband[OIII] Hα 0.02 % has a large 109 excess in HE 0433-1028 L[CII]/LFIR 8 10 excess 1σ 10 × 2σ /L 3C 326 3σ HE 1029-1831 • AGN ionization [CII] 7 10 HE 1108-2813 L cone intercepts HE 2211-3903 106 the cold SOFIA AGN Hosts galactic disk AGN Hosts High z 105 LINERs [Brisbin+15] Normal Galaxies LIRGs ULIRGs [Decarli+18] 104 108 109 1010 1011 1012 1013 1014 L /L Smirnova-Pinchukova et al. 2019 FIR Shock-excited [CII] in NGC 2445 [CII] in the ring of NGC 2445 is enhanced compared to PAHs, showing a shock excitement origin rather than star formation Fadda & Appleton, 2020, AAS Meeting 235 FIFI-LS Highlights • Nice face-on galaxies where [CII] traces star formation • Galaxies where [CII] doesn’t trace star formation • Galaxies with gas away from the plane Extraplanar [CII] in edge-on galaxies • Edge-on galaxies NGC 891 & NGC 5907 observed by Reach et al.
[Show full text]
Blue Coat SGOS Command Line Interface Reference, Version 4.2.3
Blue Coat® Systems ProxySG™ Command Line Interface Reference Version SGOS 4.2.3 Blue Coat ProxySG Command Line Interface Reference Contact Information Blue Coat Systems Inc. 420 North Mary Ave Sunnyvale, CA 94085-4121 http://www.bluecoat.com/support/contact.html [email protected] http://www.bluecoat.com For concerns or feedback about the documentation: [email protected] Copyright© 1999-2006 Blue Coat Systems, Inc. All rights reserved worldwide. No part of this document may be reproduced by any means nor modified, decompiled, disassembled, published or distributed, in whole or in part, or translated to any electronic medium or other means without the written consent of Blue Coat Systems, Inc. All right, title and interest in and to the Software and documentation are and shall remain the exclusive property of Blue Coat Systems, Inc. and its licensors. ProxySG™, ProxyAV™, CacheOS™, SGOS™, Spyware Interceptor™, Scope™, RA Connector™, RA Manager™, Remote Access™ are trademarks of Blue Coat Systems, Inc. and CacheFlow®, Blue Coat®, Accelerating The Internet®, WinProxy®, AccessNow®, Ositis®, Powering Internet Management®, The Ultimate Internet Sharing Solution®, Permeo®, Permeo Technologies, Inc.®, and the Permeo logo are registered trademarks of Blue Coat Systems, Inc. All other trademarks contained in this document and in the Software are the property of their respective owners. BLUE COAT SYSTEMS, INC. DISCLAIMS ALL WARRANTIES, CONDITIONS OR OTHER TERMS, EXPRESS OR IMPLIED, STATUTORY OR OTHERWISE, ON SOFTWARE AND DOCUMENTATION FURNISHED HEREUNDER INCLUDING WITHOUT LIMITATION THE WARRANTIES OF DESIGN, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL BLUE COAT SYSTEMS, INC., ITS SUPPLIERS OR ITS LICENSORS BE LIABLE FOR ANY DAMAGES, WHETHER ARISING IN TORT, CONTRACT OR ANY OTHER LEGAL THEORY EVEN IF BLUE COAT SYSTEMS, INC.
[Show full text]
Sleep 2.1 Manual
Sleep 2.1 Manual "If you put a million monkeys at a million keyboards, one of them will eventually write a Java program. The rest of them will write Perl programs." -- Anonymous Raphael Mudge Sleep 2.1 Manual Revision: 06.02.08 Released under a Creative Commons Attribution-ShareAlike 3.0 License (see http://creativecommons.org/licenses/by-sa/3.0/us/) You are free: • to Share -- to copy, distribute, display, and perform the work • to Remix -- to make derivative works Under the following conditions: Attribution. You must attribute this work to Raphael Mudge with a link to http://sleep.dashnine.org/ Share Alike. If you alter, transform, or build upon this work, you may distribute the resulting work only under the same, similar or a compatible license. • For any reuse or distribution, you must make clear to others the license terms of this work. The best way to do this is with a link to the license. • Any of the above conditions can be waived if you get permission from the copyright holder. • Apart from the remix rights granted under this license, nothing in this license impairs or restricts the author's moral rights. Your fair use and other rights are in no way affected by the above. Table of Contents Introduction................................................................................................. 1 I. What is Sleep?...................................................................................................1 II. Manual Conventions......................................................................................2 III.
[Show full text]
Parallel Processing Here at the School of Statistics
Parallel Processing here at the School of Statistics Charles J. Geyer School of Statistics University of Minnesota http://www.stat.umn.edu/~charlie/parallel/ 1 • batch processing • R package multicore • R package rlecuyer • R package snow • grid engine (CLA) • clusters (MSI) 2 Batch Processing This is really old stuff (from 1975). But not everyone knows it. If you do the following at a unix prompt nohup nice -n 19 some job & where \some job" is replaced by an actual job, then • the job will run in background (because of &). • the job will not be killed when you log out (because of nohup). • the job will have low priority (because of nice -n 19). 3 Batch Processing (cont.) For example, if foo.R is a plain text file containing R commands, then nohup nice -n 19 R CMD BATCH --vanilla foo.R & executes the commands and puts the printout in the file foo.Rout. And nohup nice -n 19 R CMD BATCH --no-restore foo.R & executes the commands, puts the printout in the file foo.Rout, and saves all created R objects in the file .RData. 4 Batch Processing (cont.) nohup nice -n 19 R CMD BATCH foo.R & is a really bad idea! It reads in all the objects in the file .RData (if one is present) at the beginning. So you have no idea whether the results are reproducible. Always use --vanilla or --no-restore except when debugging. 5 Batch Processing (cont.) This idiom has nothing to do with R. If foo is a compiled C or C++ or Fortran main program that doesn't have command line arguments (or a shell, Perl, Python, or Ruby script), then nohup nice -n 19 foo & runs it.
[Show full text]
Unix Quickref.Dvi
Summary of UNIX commands Table of Contents df [dirname] display free disk space. If dirname is omitted, 1. Directory and file commands 1994,1995,1996 Budi Rahardjo ([email protected]) display all available disks. The output maybe This is a summary of UNIX commands available 2. Print-related commands in blocks or in Kbytes. Use df -k in Solaris. on most UNIX systems. Depending on the config- uration, some of the commands may be unavailable 3. Miscellaneous commands du [dirname] on your site. These commands may be a commer- display disk usage. cial program, freeware or public domain program that 4. Process management must be installed separately, or probably just not in less filename your search path. Check your local documentation or 5. File archive and compression display filename one screenful. A pager similar manual pages for more details (e.g. man program- to (better than) more. 6. Text editors name). This reference card, obviously, cannot de- ls [dirname] scribe all UNIX commands in details, but instead I 7. Mail programs picked commands that are useful and interesting from list the content of directory dirname. Options: a user's point of view. 8. Usnet news -a display hidden files, -l display in long format 9. File transfer and remote access mkdir dirname Disclaimer make directory dirname The author makes no warranty of any kind, expressed 10. X window or implied, including the warranties of merchantabil- more filename 11. Graph, Plot, Image processing tools ity or fitness for a particular purpose, with regard to view file filename one screenfull at a time the use of commands contained in this reference card.
[Show full text]
The Evolution of Gandcrab Ransomware
The Evolution of GandCrab Ransomware Tamas Boczan @tamas_boczan Sr. Threat Analyst Why? Why? Why? Business Model: RaaS Panel for Affiliates Mass Delivery Methods • Email attachments - Javascript - Doc - Encrypted doc • Drive- by download Delivery: RDP, Exploits Payload: Starting Point Data collection • System Info • External IP • AV? Payload: Starting Point Data collection Connect Home • System Info • nslookup • External IP • AV? Payload: Starting Point Data collection Connect Home Preparation • System Info • nslookup • Kill Processes • External IP • AV? Payload: Starting Point Data collection Connect Home Preparation Encryption • System Info • nslookup • Kill Processes • AES • External IP • *.GDCB • AV? Payload: Starting Point Data collection Connect Home Preparation Encryption Post-Infection • System Info • nslookup • Kill Processes • AES • Shadow Copies • External IP • *.GDCB • AV? Feb 28: Europol decryptor Data collection Connect Home Preparation Encryption Post-Infection • System Info • nslookup • Kill Processes • AES • Shadow Copies • External IP • *.GDCB • AV? 7 days later: v2 Data collection Connect Home Preparation Encryption Post-Infection • System Info • nslookup • Kill Processes • AES • Shadow Copies • External IP • *.CRAB • AV? • Kernel-AV 7 weeks later: v3 Post-Infection • Shadow Copies • Wallpaper v4 Data collection Connect Home Preparation Encryption Post-Infection • System Info • nslookup • Kill Processes • AES • Shadow Copies • External IP • Salsa • Wallpaper • AV? • *.KRAB • Self-removal • SMB shares v4.1 Data collection
[Show full text]
Freebsd Command Reference
FreeBSD command reference Command structure Each line you type at the Unix shell consists of a command optionally followed by some arguments , e.g. ls -l /etc/passwd | | | cmd arg1 arg2 Almost all commands are just programs in the filesystem, e.g. "ls" is actually /bin/ls. A few are built- in to the shell. All commands and filenames are case-sensitive. Unless told otherwise, the command will run in the "foreground" - that is, you won't be returned to the shell prompt until it has finished. You can press Ctrl + C to terminate it. Colour code command [args...] Command which shows information command [args...] Command which modifies your current session or system settings, but changes will be lost when you exit your shell or reboot command [args...] Command which permanently affects the state of your system Getting out of trouble ^C (Ctrl-C) Terminate the current command ^U (Ctrl-U) Clear to start of line reset Reset terminal settings. If in xterm, try Ctrl+Middle mouse button stty sane and select "Do Full Reset" exit Exit from the shell logout ESC :q! ENTER Quit from vi without saving Finding documentation man cmd Show manual page for command "cmd". If a page with the same man 5 cmd name exists in multiple sections, you can give the section number, man -a cmd or -a to show pages from all sections. man -k str Search for string"str" in the manual index man hier Description of directory structure cd /usr/share/doc; ls Browse system documentation and examples. Note especially cd /usr/share/examples; ls /usr/share/doc/en/books/handbook/index.html cd /usr/local/share/doc; ls Browse package documentation and examples cd /usr/local/share/examples On the web: www.freebsd.org Includes handbook, searchable mailing list archives System status Alt-F1 ..
[Show full text]
System Calls & Signals
CS345 OPERATING SYSTEMS System calls & Signals Panagiotis Papadopoulos [email protected] 1 SYSTEM CALL When a program invokes a system call, it is interrupted and the system switches to Kernel space. The Kernel then saves the process execution context (so that it can resume the program later) and determines what is being requested. The Kernel carefully checks that the request is valid and that the process invoking the system call has enough privilege. For instance some system calls can only be called by a user with superuser privilege (often referred to as root). If everything is good, the Kernel processes the request in Kernel Mode and can access the device drivers in charge of controlling the hardware (e.g. reading a character inputted from the keyboard). The Kernel can read and modify the data of the calling process as it has access to memory in User Space (e.g. it can copy the keyboard character into a buffer that the calling process has access to) When the Kernel is done processing the request, it restores the process execution context that was saved when the system call was invoked, and control returns to the calling program which continues executing. 2 SYSTEM CALLS FORK() 3 THE FORK() SYSTEM CALL (1/2) • A process calling fork()spawns a child process. • The child is almost an identical clone of the parent: • Program Text (segment .text) • Stack (ss) • PCB (eg. registers) • Data (segment .data) #include <sys/types.h> #include <unistd.h> pid_t fork(void); 4 THE FORK() SYSTEM CALL (2/2) • The fork()is one of the those system calls, which is called once, but returns twice! Consider a piece of program • After fork()both the parent and the child are ..
[Show full text]
Transcript of Interviews
UNIVERSITY OF OXFORD ANNUAL REVIEW 2013/14 REALISING THE POTENTIAL The UNIQ scheme allows academically able students from state schools to experience student life at a top research-led university Transcript of interviews Alistair (mentor): UNIQ’s been running five years now and I was a student The Humanities UNIQ course and other themed courses on the very first year. I’ve now been a mentor for two allow students to dip into history and English and whatever years. There are lots of lectures, which are a bit like the they want. Or general science UNIQ courses, where ones you would have in Oxford as an undergraduate; lab they can actually spend a week deciding which of these work as well, with similar experiments; and a lot of social disciplines suits them most, or maybe they want to do a activities as well with the other students. joint or combined honours course. Fiona (mentor): Fiona: The summer school was in fact way more packed into When I was 17 doing UNIQ I thought the 21-year-olds a week than I actually find myself doing in a week at running the course, assisting on the course, were so old. Oxford. I thought they’d got everything together, they were so mature, they were all going to go and have jobs. It’s quite Selina Todd, lecturer in history: nice that they must see me in the same way, as someone The culmination of the week was finishing and handing who’s been through it, and got their act together. I think the in – and having marked – your first Oxford history essay.
[Show full text]