Commands using grep sorted by votes

Commands using grep (1,935)

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Monitor logs in Linux using Tail

Works in Ubuntu, I hope it will work on all Linux machines. For Unixes, tail should be capable of handling more than one file with '-f' option. This command line simply take log files which are text files, and not ending with a number, and it will continuously monitor those files. Putting one alias in .profile will be more useful.
This is sample output - yours may be different.
6

find /var/log -type f -exec file {} \; | grep 'text' | cut -d' ' -f1 | sed -e's/:$//g' | grep -v '[0-9]$' | xargs tail -f

mohan43u · 2009-06-03 09:47:08 11
Get all possible problems from any log files

Using the grep command, retrieve all lines from any log files in /var/log/ that have one of the problem states
This is sample output - yours may be different.
6

grep -2 -iIr "err\|warn\|fail\|crit" /var/log/*

miketheman · 2009-06-17 19:41:04 10

Check which files are opened by Firefox then sort by largest size.

Check which files are opened by Firefox then sort by largest size (in MB). You can see all files opened by just replacing grep to "/". Useful if you'd like to debug and check which extensions or files are taking too much memory resources in Firefox. Show Sample Output

FFPID=$(pidof firefox-bin) && lsof -p $FFPID | awk '{ if($7>0) print ($7/1024/1024)" MB -- "$9; }' | grep ".mozilla" | sort -rn

josue · 2009-08-16 08:58:22 7

Verify MD5SUMS but only print failures

All valid files are withheld so only failures show up. No output, all checks good.
This is sample output - yours may be different.
6

md5sum --check MD5SUMS | grep -v ": OK"

gpenguin · 2009-10-02 05:21:17 7
Google Spell Checker

I took matthewbauer's cool one-liner and rewrote it as a shell function that returns all the suggestions or outputs "OK" if it doesn't find anything wrong. It should work on ksh, zsh, and bash. Users that don't have tee can leave that part off like this: spellcheck(){ typeset y=$@;curl -sd "<spellrequest><text>$y</text></spellrequest>" https://google.com/tbproxy/spell|sed -n '/s="[1-9]"/{s/<[^>]*>/ /g;s/\t/ /g;s/ *$.*$/Suggestions: \1\n/g;p}';} Show Sample Output
This is sample output - yours may be different.
```
$ spellcheck motaive
Suggestions: motive motives mutative emotive motif

$ spellcheck now is the winter of our dicontent
Suggestions: discontent content contend

$ spellcheck panoply
OK
```
6

spellcheck(){ typeset y=$@;curl -sd "<spellrequest><text>$y</text></spellrequest>" https://www.google.com/tbproxy/spell|sed -n '/s="[0-9]"/{s/<[^>]*>/ /g;s/\t/ /g;s/ *$.*$/Suggestions: \1\n/g;p}'|tee >(grep -Eq '.*'||echo -e "OK");}

eightmillion · 2010-02-17 08:20:48 17
Show top committers for SVN repositority for today
This is sample output - yours may be different.
6

svn log -r {`date "+%Y-%m-%d"`}:HEAD|grep '^r[0-9]' |cut -d\| -f2|sort|uniq -c

ivanatora · 2010-02-18 10:41:17 4
Print Memory Utilization Percentage For a specific process and it's children

Change the name of the process and what is echoed to suit your needs. The brackets around the h in the grep statement cause grep to skip over "grep httpd", it is the equivalent of grep -v grep although more elegant. Show Sample Output
This is sample output - yours may be different.
```
RAM Used By HTTP: 50.5000%
```
6

TOTAL_RAM=`free | head -n 2 | tail -n 1 | awk '{ print $2 }'`; PROC_RSS=`ps axo rss,comm | grep [h]ttpd | awk '{ TOTAL += $1 } END { print TOTAL }'`; PROC_PCT=`echo "scale=4; ( $PROC_RSS/$TOTAL_RAM ) * 100" | bc`; echo "RAM Used by HTTP: $PROC_PCT%"

d34dh0r53 · 2010-02-26 20:29:45 8
Save xkcd to a pdf with captions

Saves to a PDF with title and alt text of comic. As asked for on http://bbs.archlinux.org/viewtopic.php?id=91100 Change xkcd.com to dynamic.xkcd.com/comics/random for a random comic.
This is sample output - yours may be different.
6

curl -sL xkcd.com | grep '<img [^>]*/><br/>' | sed -r 's|<img src="(.*)" title="(.*)" alt="(.*)" /><br/>|\1\t\2\t\3|' > /tmp/a; curl -s $(cat /tmp/a | cut -f1) | convert - -gravity south -draw "text 0,0 \"$(cat /tmp/a | cut -f2)\"" pdf:- > xkcd.pdf

matthewbauer · 2010-03-03 03:41:31 14
List .log files open by a pid

Uses lsof to display the full path of ".log" files opened by a specified PID.
This is sample output - yours may be different.
6

lsof -p 1234 | grep -E "\.log$" | awk '{print $NF}'

zlemini · 2010-03-05 11:41:28 5
Capture video of a linux desktop
This is sample output - yours may be different.
6

ffmpeg -f x11grab -s `xdpyinfo | grep 'dimensions:'|awk '{print $2}'` -r 25 -i :0.0 -sameq /tmp/out.mpg > /root/howto/capture_screen_video_ffmpeg

brubaker · 2010-03-27 21:31:34 5
Netcat ftp brute force
This is sample output - yours may be different.
6

cat list|while read lines;do echo "USER admin">ftp;echo "PASS $lines">>ftp;echo "QUIT">>ftp;nc 192.168.77.128 21 <ftp>ftp2;echo "trying: $lines";cat ftp2|grep "230">/dev/null;[ "$?" -eq "0" ]&& echo "pass: $lines" && break;done

FuRt3X · 2010-05-02 07:37:22 30
Play 89.3 @TheCurrent and get system notifications on song changes.

Plays the mp3 stream of The Current as a background job. When you are done run: fg %1 then to exit Quite possible with Growl for mac I'd guess, although have not tried. Libnotify needed for notification, stream will still work otherwise
This is sample output - yours may be different.
6

mplayer http://minnesota.publicradio.org/tools/play/streams/the_current.pls < /dev/null | grep --line-buffered "StreamTitle='.*S" -o | grep --line-buffered "'.*'" -o > mus & tail -n0 -f mus | while read line; do notify-send "Music Change" "$line";done

spiffwalker · 2010-05-09 17:51:40 3
Grep syslog today last hour

Uses date to grep de logfile for today and uses it to get the last hour logs. Can be used to get last minute logs or today's logs. Show Sample Output
This is sample output - yours may be different.
```
May 23 18:10:01 tortatil /USR/SBIN/CRON[7620]: (root) CMD (if [ -x /usr/bin/mrtg ] 
May 23 18:10:02 laptop sSMTP[7624]: Unable to locate mail
May 23 18:10:02 laptop sSMTP[7624]: Cannot open mail:25
May 23 18:10:02 laptop /USR/SBIN/CRON[7616]: (root) MAIL (mailed 1 byte of output; but got status 0x000
```
6

grep -i "$(date +%b\ %d\ %H)" syslog

rubenmoran · 2010-05-23 16:18:15 9

Grep log between range of minutes

Returns logs between HH:M[Mx-My], for example, between 13:40 and 13:45. Show Sample Output

grep -i "$(date +%b" "%d )13:4[0-5]" syslog

rubenmoran · 2010-05-23 16:30:46 6

Shows what processes need to be restarted after system upgrade

emerge,apt-get,yum... all update your system. This will at some point replace either a runtime dependency or a process (which is still running). This oneliner will list what processes need to be restarted Show Sample Output
This is sample output - yours may be different.
```
deadlib
agetty
cron
dhcpcd
irssi
mdadm
rsync
syslog-ng
tmux
```
6

deadlib() { lsof | grep 'DEL.*lib' | cut -f 1 -d ' ' | sort -u; }

Naib · 2010-11-17 12:53:30 4
Find the process you are looking for minus the grepped one

faster ;) but your idea is really cool
This is sample output - yours may be different.
6

ps -ef | grep c\\ommand

ioggstream · 2011-01-04 11:43:14 4
Using NMAP to check if a port is open or close

Using NMAP to check to see if port 22(SSH) is open on servers and network devices. Show Sample Output
This is sample output - yours may be different.
```
Host: 192.168.0.254 ()   Ports: 22/open/tcp//ssh///
Host: 192.168.0.252 ()   Ports: 22/closed/tcp//ssh///
```
6

nmap -oG - -T4 -p22 -v 192.168.0.254 | grep ssh

SeeFor · 2011-01-11 16:12:23 3
Auto Get Missing Launchpad Keys

You can choose these mirror servers to get gpg keys, if the official one ever goes offline keyserver.ubuntu.com pool.sks-keyservers.net subkeys.pgp.net pgp.mit.edu keys.nayr.net keys.gnupg.net wwwkeys.en.pgp.net #(replace with your country code fr, en, de,etc)
This is sample output - yours may be different.
6

sudo apt-get update 2> /tmp/keymissing; for key in $(grep "NO_PUBKEY" /tmp/keymissing |sed "s/.*NO_PUBKEY //"); do echo -e "\nProcessing key: $key"; gpg --keyserver pool.sks-keyservers.net --recv $key && gpg --export --armor $key |sudo apt-key add -; done

Bonster · 2011-03-30 08:18:54 8
List your MACs address
This is sample output - yours may be different.
6

ifconfig eth0 | grep -o -E '([[:xdigit:]]{1,2}:){5}[[:xdigit:]]{1,2}'

rubo77 · 2011-04-28 18:33:45 4
prettier "cal" command

Displays the same output as "cal", but with the current day highlighted (probably dependent on gnu grep, as I'm not sure other grep's support the "--color=auto" option). Tested and working on Ubuntu 11 and OSX Lion. Show Sample Output
This is sample output - yours may be different.
```
   November 2011
Su Mo Tu We Th Fr Sa
       1  2  3  4  5
 6  7  8  9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30
```
6

cal |grep -A7 -B7 --color=auto $(date +%d)

4fthawaiian · 2011-11-26 22:13:12 35
Find out how old a web page is

I used to use the Firefox "View page info" feature a lot to determine how stale the web page I was looking at was. Now that I use mostly Chrome I miss that feature, so here is a command line alternative using wget. The -S says to display the server response, the --spider says to not download any files/pages, just fetch the header. The output goes to stderr, so to grep it you use 2>&1 to combine the stderr stream with stdout, the pipe that to grep for Last-Modified. You can use curl instead if you have it installed, like this: curl --head -s http://osswin.sourceforge.net | grep Mod Show Sample Output
This is sample output - yours may be different.
```
  Last-Modified: Wed, 08 Feb 2012 20:14:53 GMT
```
6

wget -S --spider http://osswin.sourceforge.net/ 2>&1 | grep Mod

dmmst19 · 2012-04-18 03:43:33 6
download 10 random wallpapers from google

you may want &hl=en for &hl=es for the language you may want imgsz=xxlarge for imgsz=large or whatever filter you may want q=apples or whatever
This is sample output - yours may be different.
6

for i in {1..10};do wget $(wget -O- -U "" "http://images.google.com/images?imgsz=xxlarge&hl=en&q=wallpaper+HD&start=$(($RANDOM%900+100))" --quiet | grep -oe 'http://[^"]*\.jpg' | head -1);done

dzup · 2012-07-26 10:42:13 6
Examine processes generating traffic on your website

I often have to google this so I put it here for quick reference.
This is sample output - yours may be different.
6

netstat -np | grep -v ^unix

UnklAdM · 2015-11-09 17:22:30 16
remove comments (even those starting with spaces), empty lines (even those containing spaces) in one grep command

useful for discarding even those comments which start with blanks or those empty lines which contain blanks Show Sample Output
This is sample output - yours may be different.
```
[root@docker ~]# grep -vE '^\s*(#|$)' /etc/nsswitch.conf
passwd:     files sss
shadow:     files sss
group:      files sss
hosts:      files dns myhostname
bootparams: nisplus [NOTFOUND=return] files
ethers:     files
netmasks:   files
networks:   files
protocols:  files
rpc:        files
services:   files sss
netgroup:   nisplus sss
publickey:  nisplus
automount:  files nisplus sss
aliases:    files nisplus
```
6

grep -vE '^\s*(#|$)' textfile

acavagni · 2019-03-05 21:40:02 165
Listing today’s files only
This is sample output - yours may be different.
6

ls -al --time-style=+%D| grep `date +%D`

wuseman1 · 2019-07-07 00:29:04 53
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Find usb device in realtime

Using this command you can track a moment when usb device was attached.

Print every Nth line

Sometimes commands give you too much feedback. Perhaps 1/100th might be enough. If so, every() is for you. $ my_verbose_command | every 100 will print every 100th line of output. Specifically, it will print lines 100, 200, 300, etc If you use a negative argument it will print the *first* of a block, $ my_verbose_command | every -100 It will print lines 1, 101, 201, 301, etc The function wraps up this useful sed snippet: $ ... | sed -n '0~100p' don't print anything by default $ sed -n starting at line 0, then every hundred lines ( ~100 ) print. $ '0~100p' There's also some bash magic to test if the number is negative: we want character 0, length 1, of variable N. $ ${N:0:1} If it *is* negative, strip off the first character ${N:1} is character 1 onwards (second actual character).

a function to find the fastest DNS server

http://public-dns.info gives a list of online dns servers. you need to change the country in url (br in this url) with your country code. this command need some time to ping all IP in list.

Find usb device in realtime

Using this command you can track a moment when usb device was attached.

command line fu roulette

retrieves the html from a random command line fu page, then finds commands on the page and prints them alternatively, pipe to bash (add "| bash" to the end) to execute the command (very risky) edit: had to adjust to properly display the portion that replaces HTML characters (e.g. " -> ")

Check if network cable is plugged in and working correctly

with 'mii-tool -w eth0' you can watch the interface for changes of the link status

Which processes are listening on a specific port (e.g. port 80)

swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Perl oneliner to print access rights in octal format

This prints file access rights in octal - useful when "stat" is unavailable.

Count number of files in a directory

Rename file to same name plus datestamp of last modification.

FILENAME=nohup.out mv -iv $FILENAME{,.$(stat -c %Y $FILENAME)} does it help ?

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Commands using grep (1,935)

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