Commands tagged grep (409)

  • Grep for a named process. Show Sample Output


    -4
    psgrep() { if [ ! -z $1 ]; then echo "Grepping for processes matching $1..." ps aux | grep -i $1 | grep -v grep; else echo "!! Need name to grep for"; fi }
    evenme · 2010-02-27 13:47:28 7
  • Suppose you have 11 marbles, 4 of which are red, the rest being blue. The marbles are indistinguishable, apart from colour. How many different ways are there to arrange the marbles in a line? And how many ways are there to arrange them so that no two red marbles are adjacent? There are simple mathematical solutions to these questions, but it's also possible to generate and count all possibilities directly on the command line, using little more than brace expansion, grep and wc! The answer to the question posed above is that there are 330 ways of arranging the marbles in a line, 70 of which have no two red marbles adjacent. See the sample output. To follow the call to marbles 11 4: after c=''; for i in $(seq $1); do c+='{b,r}'; done;, $c equals {b,r}{b,r}{b,r}{b,r}{b,r}{b,r}{b,r}{b,r}{b,r}{b,r}{b,r} After x=$(eval echo $c), and brace expansion, $x equals bbbbbbbbbbb bbbbbbbbbbr ... rrrrrrrrrrb rrrrrrrrrrr, which is all 2^11 = 2048 strings of 11 b's and r's. After p=''; for i in $(seq $2); do p+='b*r'; done;, $p equals b*rb*rb*rb*r Next, after y=$(grep -wo "${p}b*" Finally, grep -vc 'rr' Show Sample Output


    -4
    marbles () { c=''; for i in $(seq $1); do c+='{b,r}'; done; x=$(eval echo $c); p=''; for i in $(seq $2); do p+='b*r'; done; y=$(grep -wo "${p}b*" <<< $x); wc -l <<< "$y"; grep -vc 'rr' <<< "$y"; }
    quintic · 2010-08-27 23:04:33 3
  • Ok so it's rellay useless line and I sorry for that, furthermore that's nothing optimized at all... At the beginning I didn't managed by using netstat -p to print out which process was handling that open port 4444, I realize at the end I was not root and security restrictions applied ;p It's nevertheless a (good ?) way to see how ps(tree) works, as it acts exactly the same way by reading in /proc So for a specific port, this line returns the calling command line of every thread that handle the associated socket


    -5
    p=$(netstat -nate 2>/dev/null | awk '/LISTEN/ {gsub (/.*:/, "", $4); if ($4 == "4444") {print $8}}'); for i in $(ls /proc/|grep "^[1-9]"); do [[ $(ls -l /proc/$i/fd/|grep socket|sed -e 's|.*\[\(.*\)\]|\1|'|grep $p) ]] && cat /proc/$i/cmdline && echo; done
    j0rn · 2009-04-30 12:39:48 639
  • Tail is much faster than sed, awk because it doesn't check for regular expressions. Show Sample Output


    -5
    tail -n +<N> <file> | head -n 1
    qweqq · 2011-09-30 08:30:30 6

  • -6
    grep -A 3 -i "example" demo_text
    techie · 2013-05-09 08:20:31 5
  • I know how hard it is to find an old command running through all the files because you couldn't remember for your life what it was. Heres the solution!! Grep the history for it. depending on how old the command you can head or tail or if you wanted to search all because you cannot think how long ago it was then miss out the middle part of the command. This is a very easy and effective way to find that command you are looking for.


    -9
    cat .bash_history | tail -100 | grep {command}
    techie · 2013-04-10 10:40:52 8
  • Normally, if you just want to see directories you'd use brianmuckian's command 'ls -d *\', but I ran into problems trying to use that command in my script because there are often multiple directories per line. If you need to script something with directories and want to guarantee that there is only one entry per line, this is the fastest way i know Show Sample Output


    -10
    ls -l | grep ^d | sed 's:.*\ ::g'
    LinuxMan · 2011-08-06 23:52:46 9

  • -10
    grep -r <searchterm> *
    totti · 2012-02-08 11:48:08 7
  • David thanks for that grep inside! here is mine version: psgrep() { case ${1} in ( -E | -e ) local EXTENDED_REGEXP=1 shift 1 ;; *) local EXTENDED_REGEXP=0 ;; esac if [[ -z ${*} ]] then echo "psgrep - grep for process(es) by keyword" >&2 echo "Usage: psgrep [-E|-e] ... " >&2 echo "" >&2 echo "option [-E|-e] enables full extended regexp support" >&2 echo "without [-E|-e] plain strings are looked for" >&2 return 1 fi \ps -eo 'user,pid,pcpu,command' w | head -n1 local ARG='' if (( ${EXTENDED_REGEXP} == 0 )) then while (( ${#} > 0 )) do ARG="${1}" shift 1 local STRING=${ARG} local LENGTH=$(expr length ${STRING}) local FIRSCHAR=$(echo $(expr substr ${STRING} 1 1)) local REST=$(echo $(expr substr ${STRING} 2 ${LENGTH})) \ps -eo 'user,pid,pcpu,command' w | grep "[${FIRSCHAR}]${REST}" done else \ps -eo 'user,pid,pcpu,command' w | grep -iE "(${*})" fi }


    -10
    psgrep() ... func to long, please look under "description"
    Xk2c · 2015-01-01 02:58:48 8
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Stoppable sleep
A nice way to interrupt a sleep with a signal.

Copy an element from the previous command
'n' is a non-negative integer. Using 0 will expand to the name of the previous command.

Annoying PROMPT_COMMAND animation
unset PROMPT_COMMAND to disable.

Use /dev/full to test language I/O-failsafety
The Linux /dev/full file simulates a "disk full" condition, and can be used to verify how a program handles this situation. In particular, several programming language implementations do not print error diagnostics (nor exit with error status) when I/O errors like this occur, unless the programmer has taken additional steps. That is, simple code in these languages does not fail safely. In addition to Perl, C, C++, Tcl, and Lua (for some functions) also appear not to fail safely.

Remove color codes (special characters) with sed
Removes ANSI color and end of line codes to the [{attr1};...;{attrn}m format.

Terminal Escape Code Zen - Strace and Tput
Depending on the TERM, the terminfo version, ncurses version, etc.. you may be using a varied assortment of terminal escape codes. With this command you can easily find out exactly what is going on.. This is terminal escape zen! $ ( 2>&2 strace -f -F -e write -s 1000 sh -c 'echo -e "initc\nis2\ncnorm\nrmso\nsgr0" | tput -S' 2>&1 ) | grep -o '"\\[^"]*"' --color=always "\33]4;%p1%d;rgb:%p2%{255}%*%{1000}%/%2.2X/%p3%{255}%*%{1000}%/%2.2X/%p4%{255}%*%{1000}%/%2.2X\33\\\33[!p\33[?3;4l\33[4l\33>\33[?12l\33[?25h\33[27m\33(B\33[m" Lets say you want to find out what you need to echo in order to get the text to blink.. $ echo -e "`tput blink`This will blink`tput sgr0` This wont" Now you can use this function instead of calling tput (tput is much smarter for portable code because it works differently depending on the current TERM, and tput -T anyterm works too.) to turn that echo into a much faster executing code. tput queries files, opens files, etc.. but echo is very strait and narrow. So now you can do this: $ echo -e "\33[5mThis will blink\33(B\33[m This wont" More at http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html

Show a curses based menu selector
Not so much handy by itself, but very nice in shell scripts. This makes you a handy ncurses based checklist. Much like terminal installers, just use the arrow keys and hit 'Space' to adjust the selections. Returns all selected tags as strings, with no newline at the end. So, your output will be something like: "one" "two" "three" "four" "etc" For those who prefer bash expansion over gratuitious typing: $ whiptail --checklist "Simple checkbox menu" 12 35 3 $(echo {one,two,three,four}" '' 0"} ) Things to note: The height must includes the outer border and padding: add 7 to however many items you want to show up at the same time. If the status is 1, it will be selected by default. anything else, will be deselected.

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" }

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"

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" }


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