Commands by DoNotRememberMe (8)

  • Watch any command (pipes ok, quotes be careful) and keep history in a file. Good for watching and recording any kind of status or error condition, file creations, etc. The choice of "who" as CMD was just to show an obvious usage. Uses plenty of shell tricks that can be disassembled for simpler stuff. It's deliberately not perfect, but it is generic, and can be customized for your own uses. Had to shorten a little to meet 255 chars. Better than "watch" how? It keeps a date log of what is going on, and tee'd output is plain-text. Show Sample Output


    0
    CMD="who";SEC=1;N=0;OLD="";NEW=""; while `sleep $SEC`; do OLD="$NEW"; NEW="$(eval $CMD)"; DIFF=`diff <( echo "$OLD" ) <( echo "$NEW" )`; if [ -n "$DIFF" ]; then date; echo "Diff #$N (${SEC}s): $CMD"; echo "$DIFF"; fi; N=$[$N+1]; done | tee /tmp/keepr
    DoNotRememberMe · 2010-11-15 19:55:39 0
  • Get there by going backwards and forgetting the numbers.


    5
    seq -s" " -50 -1 | tr -dc -
    DoNotRememberMe · 2010-03-25 06:00:24 0
  • If you want to relocate a package on your own, or you just want to know what those PREIN/UN and POSTIN/UN scripts will do, this will dump out all that detail simply. You may want to expand the egrep out other verbose flags like CHANGELOGTEXT etc, as your needs require. It isn't clear, but the formatting around $tag is important: %{$tag} just prints out the first line, while [%{$tag }] iterates thru multi-line output, joining the lines with a space (yes, there's a space between the g and } characters. To break it out for all newlines, use [%{$tag\n}] but the output will be long. This is aside from rpm2cpio | cpio -ivd to extract the package files.


    0
    rpm --querytags | egrep -v HEADERIMMUTABLE | sort | while read tag ; do rpm -q --queryformat "$tag: [%{$tag} ]\n" -p $SomeRPMfile ; done
    DoNotRememberMe · 2010-03-25 05:40:48 0
  • The example is a little bit bogus, but applies to any command that takes a while interactively, or might be a bit of a drag on system resources. Once the command's output is saved to a variable, you can then echo "$OUTPUT" to see it in multi-line glory after that. The use of double-quotes around the backticks and during the variable expansion disables any IFS conversion during those two operations. Very useful for reporting that might pull different lines out, like from dmidecode, inq or any other disk detail command. The only caveat is that storing too much in a variable might make your shell process grow.


    0
    OUTPUT="`find / -type f`" ; echo "$OUTPUT" | grep sysrq ; echo "$OUTPUT" | grep sysctl ; echo "$OUTPUT" | less
    DoNotRememberMe · 2010-03-25 05:02:10 0
  • Something to stuff in an alias when you are working in multiple environments. The double-pipe OR will fall through until one of the commands succeeds, and the rest won't be executed. Any STDERR will fall out, but the STDOUT from the correct command will bubble out of the parenthesis to the less command, or some other command you specify.


    5
    ( zcat $FILE || gzcat $FILE || bzcat2 $FILE ) | less
    DoNotRememberMe · 2010-03-17 03:14:48 2
  • Searches your $PATH for whatever you substitute for bash, though not sure if this will work if you substitute a different shell for bash! Show Sample Output


    6
    find ${PATH//:/ } -name \*bash\*
    DoNotRememberMe · 2010-03-16 04:26:27 1
  • When your wtmp files are being logrotated, here's an easy way to unpack them all on the fly to see more than a week in the past. The rm is the primitive way to prevent symlink prediction attack.


    5
    ( last ; ls -t /var/log/wtmp-2* | while read line ; do ( rm /tmp/wtmp-junk ; zcat $line 2>/dev/null || bzcat $line ) > /tmp/junk-wtmp ; last -f /tmp/junk-wtmp ; done ) | less
    DoNotRememberMe · 2010-03-16 04:17:16 0
  • No need to type out the full OR clause if you know which OS you're on, but this is easy cut-n-paste or alias to get top ten directories by singleton. To avoid the error output from du -xSk you could always 2>/dev/null but you might miss relevant STDERR.


    4
    ( du -xSk || du -kod ) | sort -nr | head
    DoNotRememberMe · 2010-03-16 04:05:14 1

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list block devices
Shows all block devices in a tree with descruptions of what they are.

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Block all IP addresses and domains that have attempted brute force SSH login to computer
Searches all log files (including archived bzip2 files) for invalid user and PAM authentication errors, both of which are indicative of brute force attempts at logging into computer. A list of all unique IP addresses and domain names is appended to hosts.deny. The command (and grep error messages) will work on Mac OS X 10.6, small adjustments may be needed for other OSs.

Blue Matrix
Same as original, but works in bash

Multi-thread any command
For instance: $ find . -type f -name '*.wav' -print0 |xargs -0 -P 3 -n 1 flac -V8 will encode all .wav files into FLAC in parallel. Explanation of xargs flags: -P [max-procs]: Max number of invocations to run at once. Set to 0 to run all at once [potentially dangerous re: excessive RAM usage]. -n [max-args]: Max number of arguments from the list to send to each invocation. -0: Stdin is a null-terminated list. I use xargs to build parallel-processing frameworks into my scripts like the one here: http://pastebin.com/1GvcifYa

Exclude grep from your grepped output of ps (alias included in description)
Surround the first letter of what you are grepping with square brackets and you won't have to spawn a second instance of grep -v. You could also use an alias like this (albeit with sed): alias psgrep='ps aux | grep $(echo $1 | sed "s/^\(.\)/[\1]/g")'

Set Time Zone in Ubuntu
Reconfigures time zone in Ubuntu, which I cannot figure out how to do through the GUI. Worked like a charm to set my time zone to CEST from EDT.

Scan Subnet for IP and MAC addresses

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.

Calculate days on which Friday the 13th occurs (inspired from the work of the user justsomeguy)
Friday is the 5th day of the week, monday is the 1st. Output may be affected by locale.


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