Commands tagged Linux (254)

  • Compare the content of the files in the current directory with files of the same name in the duplicate directory. Pop Quiz: You have a duplicate of a directory with files of the same name that might differ. What do you do? You could use diff to compare the directories, but that's boring and it isn't as clever as find -print0 with xargs. Note: You must omit stderr redirect 2>/dev/null to see the list of missing files from DUPDIR, if any. Hint: Redirect stderr to a new file to produce a more readable list of files that are missing from DUPDIR. Warning: This doesn't tell you if DUPDIR contains files not found in the current directory so don't delete DUPDIR. Show Sample Output


    0
    find . -maxdepth 1 -mindepth 1 -print0 | xargs -0 -n 1 -I % cmp % /DUPDIR/% 2>/dev/null
    RiskNerd · 2018-07-08 02:25:57 0
  • Assumes you've downloaded Toni Corvera's vcs script (http://p.outlyer.net/vcs), have it in your PATH, and have installed the script's dependencies. Generates a video contact sheet of 24 thumbnails and 3 thumbnails per column. The bold font and white-on-black color scheme keeps the text readable at the chosen 70% JPEG compression quality, which keeps the file size at a manageable level. You can go even lower with the quality and get a good looking result.


    2
    vcs -c 3 -H 220 -n 24 -dt -ds -dp -j --anonymous -O bg_heading=black -O bg_sign=black -O fg_heading=white -O fg_heading=white -O fg_sign=white -O fg_title=white -O font_heading=DejaVu-Sans-Bold -O quality=70
    Negate · 2018-06-06 00:49:25 0
  • Command to raise the volume. From https://wiki.archlinux.org/index.php/PulseAudio#Keyboard_volume_control


    0
    pactl set-sink-mute 0 false ; pactl set-sink-volume 0 +5%
    MaxLanar · 2017-05-13 13:02:50 0
  • This is a commodity one-liner that uses ShellCheck to assure some quality on bash and sh scripts under a specific directory. It ignores the files in .git directory. Just substitute "./.git/*" with "./.svn/*" for older and booring centralized version control. Just substitute ShellCheck with "rm" if your scripts are crap and you want to get rid of them :)


    5
    find . -type f ! -path "./.git/*" -exec sh -c "head -n 1 {} | egrep -a 'bin/bash|bin/sh' >/dev/null" \; -print -exec shellcheck {} \;
    brx75x · 2017-03-16 08:43:56 3
  • To allow recursivity : find -type f -exec md5sum '{}' ';' | sort | uniq -c -w 33 | sort -gr | head -n 5 | cut -c1-7,41- Display only filenames : find -maxdepth 1 -type f -exec md5sum '{}' ';' | sort | uniq -c -w 33 | sort -gr | head -n 5 | cut -c43- Show Sample Output


    0
    find -maxdepth 1 -type f -exec md5sum '{}' ';' | sort | uniq -c -w 33 | sort -gr | head -n 5 | cut -c1-7,41-
    MaDCOw · 2017-02-09 11:36:31 0
  • uses the wonderful 'pv' command to give a progress bar when copying one partition to another. Amazing for long running dd commands Show Sample Output


    0
    pv -tpreb /dev/sdc2 | dd of=/dev/sdb2 bs=64K conv=noerror,sync
    4fthawaiian · 2016-12-22 03:18:09 0

  • 0
    find . -mtime +30 -exec ls -all "{}" \; | awk '{COUNTER+=$5} END {SIZE=COUNTER/1024/1024; print "size sum of found files is: " SIZE "MB"}'
    breign · 2016-10-28 08:05:57 0
  • Results will be shown in columns. Only different files and files in one directory that is not in the other will be shown.


    0
    diff -y --suppress-common-lines <(sort -k2 <(md5deep -r -b directory1)) <(sort -k2 <(md5deep -r -b directory2))
    MeLoPasoPipa · 2016-08-18 09:17:16 0
  • Don't use. This defines a function `:` that will create two more of itself, infinitely in the background. While this function is itself defined in the background, it is run up in the front.


    0
    :(){ :|:& }&:
    tox123 · 2016-08-05 15:45:10 0
  • As output, checksums and filenames will be printed.


    0
    diff <(sort <(md5deep -r /directory/1/) | awk -F '/' '{print $1 $NF}') <(sort <(md5deep -r /directory/2/) | awk -F '/' '{print $1 $NF}')
    linux_noob · 2016-06-06 20:05:01 0
  • Trace python statement execution and syscalls invoked during that simultaneously Show Sample Output


    0
    strace python -m trace --trace myprog.py | grep -v 'write(1,'
    roolebo · 2016-05-27 21:01:01 0
  • This command will find any named file types in / between two dates then will list all the metadata of those files in long format and human readable form. Adding a 't' flag to the ls command sorts the files by modified time. After all that the head -5 lists the first 5 which can be changed.


    0
    ls -laht `find / -name "*.*" -type f -newermt "2016-04-05" ! -newermt "2016-04-10"`|head -5
    ubercoo · 2016-04-19 14:26:23 0
  • The output format is given by the -printf parameter: %T@ = modify time in seconds since Jan. 1, 1970, 00:00 GMT, with fractional part. Mandatory, hidden in the end. %TY-%Tm-%Td %TH:%TM:%.2TS = modify time as YYYY-MM-DD HH:MM:SS. Optional. %p = file path Refer to http://linux.die.net/man/1/find for more about -printf formatting. ------------------------ sort -nr = sort numerically and reverse (higher values - most recent timestamp - first) head -n 5 = get only 5 first lines (change 5 to whatever you want) cut -f2- -d" " = trim first field (timestamp, used only for sorting) ------------------------ Very useful for building scripts for detecting malicious files upload and malware injections. Show Sample Output


    6
    find . -type f -printf '%T@ %TY-%Tm-%Td %TH:%TM:%.2TS %p\n' | sort -nr | head -n 5 | cut -f2- -d" "
    paulera · 2016-03-23 11:56:39 0
  • This command telnet and and looks for a line starting with "SSH" - works for OpenSSH since the SSH banner is something like "SSH-2.0-OpenSSH_6.0p1 Debian-4+deb7u3". Then it triggers an action accordingly. It can be packed as a script file to echo 0/1 indicating the SSH service availability: if [[ "$(sleep 1 | telnet -c <host> <port> 2>&1 | grep '^SSH')" == SSH* ]]; then echo 1; else echo 0; fi; Alternative uses: Trigger an action when server is UP (using &&): [[ "$(sleep 1 | telnet -c <host> <port> 2>&1 | grep '^SSH')" == SSH* ]] && <command when up> Trigger an action when server is DOWN (using ||): [[ "$(sleep 1 | telnet -c <host> <port> 2>&1 | grep '^SSH')" == SSH* ]] || <command when down>


    0
    $if [[ "$(sleep 1 | telnet -c <host> <port> 2>&1 | grep '^SSH')" == SSH* ]]; then <command when up>; else <command when down>; fi;
    paulera · 2016-02-02 13:06:51 2
  • I had to reconfigure all of my 150 domains to use "localhost" as IMAP/SMTP server instead of mail.[domain]. This little thing did the job in a fraction of a second!


    0
    sed -i -E 's/mail\..*/localhost\"/g' *
    Blagus · 2016-01-15 14:48:32 0

  • 0
    ss -s | sed -n '/.*estab \([0-9]*\).*/s//\1/p'
    phrik · 2015-12-08 12:35:22 0

  • 0
    find / -name \*.php -exec grep -Hn preg_replace {} \;|grep /e|grep POST
    UnklAdM · 2015-10-28 16:10:23 0
  • Show the command line for a PID with ps


    3
    ps h -o %a 21679
    BeniBela · 2015-09-27 11:00:07 2

  • 2
    tr '\0' ' ' </proc/21679/cmdline ; echo
    pdxdoughnut · 2015-09-25 22:08:31 5

  • 0
    echo "\"$(objdump -d BINARY | grep '[0-9a-f]:' | cut -d$'\t' -f2 | grep -v 'file' | tr -d " \n" | sed 's/../\\x&/g')\""
    reiderroque · 2015-09-25 20:21:26 0
  • If you cat the file, all the parts of the command line are bunched up. If you use tr to convert the nulls to spaces, you're still left without a newline unless you add another step. This command does everything for you. Show Sample Output


    7
    xargs -0a /proc/27288/cmdline echo
    dennisw · 2015-09-25 17:35:11 6
  • Needs to be run in a battery sysfs dir, eg. /sys/class/power_supply/BAT0 on my system. Displays the battery's current charge and the rate per-second at which energy is {dis,}charging. All values are displayed as percentages of "full" charge. The first column is the current charge. The second is the rate of change averaged over the entire lifetime of the command (or since the AC cable was {un,}plugged), and the third column is the rate of change averaged over the last minute (controlled by the C=60 variable passed to awk). The sample output captures a scenario where I ran 'yes' in another terminal to max out a CPU. My battery was at 76% charge and you can see the energy drain starts to rise above 0.01% per-second as the cpu starts working and the fan kicks in etc. While idle it was more like 0.005% per-second. I tried to use this to estimate the remaining battery life/time until fully charged, but found it to be pretty useless... As my battery gets more charged it starts to charge slower, which meant the estimate was always wrong. Not sure if that's common for batteries or not. Show Sample Output


    -1
    while cat energy_now; do sleep 1; done |awk -v F=$(cat energy_full) -v C=60 'NR==1{P=B=$1;p=100/F} {d=$1-P; if(d!=0&&d*D<=0){D=d;n=1;A[0]=B=P}; if(n>0){r=g=($1-B)/n;if(n>C){r=($1-A[n%C])/C}}; A[n++%C]=P=$1; printf "%3d %+09.5f %+09.5f\n", p*$1, p*g, p*r}'
    sqweek · 2015-09-19 15:45:40 0
  • Ever needed to test firewalls but didn't have netcat, telnet or even FTP? Enter /dev/tcp, your new best friend. /dev/tcp/(hostname)/(port) is a bash builtin that bash can use to open connections to TCP and UDP ports. This one-liner opens a connection on a port to a server and lets you read and write to it from the terminal. How it works: First, exec sets up a redirect for /dev/tcp/$server/$port to file descriptor 5. Then, as per some excellent feedback from @flatcap, we launch a redirect from file descriptor 5 to STDOUT and send that to the background (which is what causes the PID to be printed when the commands are run), and then redirect STDIN to file descriptor 5 with the second cat. Finally, when the second cat dies (the connection is closed), we clean up the file descriptor with 'exec 5>&-'. It can be used to test FTP, HTTP, NTP, or can connect to netcat listening on a port (makes for a simple chat client!) Replace /tcp/ with /udp/ to use UDP instead.


    15
    exec 5<>/dev/tcp/time.nist.gov/13; cat <&5 & cat >&5; exec 5>&-
    tyzbit · 2015-07-30 21:12:38 9
  • Clears your clipboard if xsel is installed on your machine. If your xsel is dumb, you can also use xsel --clear --clipboard


    1
    xsel -bc
    benjabean1 · 2015-02-26 01:11:03 0
  • Use this command to execute the contents of http://www.example.com/automation/remotescript.sh in the local environment. The parameters are optional. Alterrnatives to wget: CURL: curl -s http://www.example.com/automation/remotescript.sh | bash /dev/stdin param1 param2 W3M: w3m -dump http://www.example.com/automation/remotescript.sh | bash /dev/stdin [param1] [param2] LYNX: lynx -source http://www.example.com/automation/remotescript.sh | bash /dev/stdin [param1] [param2]


    0
    wget -q -O - http://www.example.com/automation/remotescript.sh | bash /dev/stdin parameter1 parameter2
    paulera · 2015-02-16 16:55:09 5
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quickly formats a fat partition. usefull for flash drives

Find the package that installed a command

Follow tail by name (fix for rolling logs with tail -f)
If you use 'tail -f foo.txt' and it becomes temporarily moved/deleted (ie: log rolls over) then tail will not pick up on the new foo.txt and simply waits with no output. 'tail -F' allows you to follow the file by it's name, rather than a descriptor. If foo.txt disappears, tail will wait until the filename appears again and then continues tailing.

Easily scp a file back to the host you're connecting from
Place in .bashrc and invoke like this: "mecp /path/to/file", and it will copy the specified file(s) back to the desktop of the host you're ssh'ing in from. To easily upload a file from the host you're ssh'ing in from use this: ucp (){ scp ${SSH_CLIENT%% *}:Desktop/upload/* .; }

Not a kismet replacement...
If you're like some individuals who rely on ndiswrapper and cannot use kismet, this command may be of service. watch -n .5 "iwlist wlan0 scan | egrep 'ESSID|Encryption'" Or... watch -n .5 "iwlist wlan0 scan | egrep 'ESSID|Encryption' | egrep 'linksys'" :-) Hopefully you'll find some dd-wrt compatible routers.

find all active IP addresses in a network
You send a unicast ICMP packet to each host. Many firewalls will drop that ICMP. However, in order to send the ICMP, you'll have first done an ARP request and the remote machine is unlikely to ignore that, so the computer will be in your ARP table.

Install pip with Proxy
Installs pip packages defining a proxy

Get the next weekday for an 'at' command
Line can be modified as needed. This considers weekdays to be Mon-Fri. If run any working day it'll provide a parameters for the next working day for "at". "beep" provided as a sample command. This can be modified easily to include wait time. If you need something to run "D" days after today: # D=4;if [ $(date +%u --date="${D} days") -lt 5 ];then AT="+${D} days";else AT="next monday";fi; echo "beep" | at noon ${AT}

Search for a string inside all files in the current directory

Get current Xorg resolution via xrandr


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