Commands tagged echo (86)

  • Tee can be used to split a pipe into multiple streams for one or more process to work it. You can add more " >()" for even more fun. Show Sample Output


    33
    echo "tee can split a pipe in two"|tee >(rev) >(tr ' ' '_')
    axelabs · 2010-08-14 20:38:59 3
  • Run the alias command, then issue ps aux | head and resize your terminal window (putty/console/hyperterm/xterm/etc) then issue the same command and you'll understand. ${LINES:-`tput lines 2>/dev/null||echo -n 12`} Insructs the shell that if LINES is not set or null to use the output from `tput lines` ( ncurses based terminal access ) to get the number of lines in your terminal. But furthermore, in case that doesn't work either, it will default to using the deafault of 12 (-2 = 10). The default for HEAD is to output the first 10 lines, this alias changes the default to output the first x lines instead, where x is the number of lines currently displayed on your terminal - 2. The -2 is there so that the top line displayed is the command you ran that used HEAD, ie the prompt. Depending on whether your PS1 and/or PROMPT_COMMAND output more than 1 line (mine is 3) you will want to increase from -2. So with my prompt being the following, I need -7, or - 5 if I only want to display the commandline at the top. ( http://www.askapache.com/linux-unix/bash-power-prompt.html ) 275MB/748MB [7995:7993 - 0:186] 06:26:49 Thu Apr 08 [askapache@n1-backbone5:/dev/pts/0 +1] ~ In most shells the LINES variable is created automatically at login and updated when the terminal is resized (28 linux, 23/20 others for SIGWINCH) to contain the number of vertical lines that can fit in your terminal window. Because the alias doesn't hard-code the current LINES but relys on the $LINES variable, this is a dynamic alias that will always work on a tty device. Show Sample Output


    26
    alias head='head -n $((${LINES:-`tput lines 2>/dev/null||echo -n 12`} - 2))'
    AskApache · 2010-04-08 22:37:06 7
  • This version uses Pipes, but is easier for the common user to grasp... instead of using sed or some other more complicated method, it uses the tr command Show Sample Output


    15
    echo $PATH | tr \: \\n
    crk · 2009-09-09 02:10:04 2
  • pings a server once per second, and beeps when the server is unreachable. Basically the opposite of: ping -a server-or-ip.com which would beep when a server IS reachable. You could also substitute beep with any command, which makes this a powerful alternative to ping -a: while true; do [ "$(ping -c1W1w1 server-or-ip.com 2>/dev/null | awk '/received/ {print $4}')" = 1 ] && date || echo 'server is down!'; sleep 1; done which would output the date and time every sec until the ping failed, in which case it would echo. Notes: Requires beep package. May need to run as root (beep uses the system speaker) Tested on Ubuntu which doesn't have beep out of the box... sudo apt-get install beep


    14
    while true; do [ "$(ping -c1W1w1 server-or-ip.com | awk '/received/ {print $4}')" != 1 ] && beep; sleep 1; done
    sudopeople · 2009-03-31 20:47:56 4

  • 14
    echo "uptime" | tee >(ssh host1) >(ssh host2) >(ssh host3)
    gutoyr · 2010-08-20 16:22:57 2
  • Very useful in shell scripts because you can run a task nicely in the background using job-control and output progress until it completes. Here's an example of how I use it in backup scripts to run gpg in the background to encrypt an archive file (which I create in this same way). $! is the process ID of the last run command, which is saved here as the variable PI, then sleeper is called with the process id of the gpg task (PI), and sleeper is also specified to output : instead of the default . every 3 seconds instead of the default 1. So a shorter version would be sleeper $!; The wait is also used here, though it may not be needed on your system. echo ">>> ENCRYPTING SQL BACKUP" gpg --output archive.tgz.asc --encrypt archive.tgz 1>/dev/null & PI=$!; sleeper $PI ":" 3; wait $PI && rm archive.tgz &>/dev/null Previously to get around the $! not always being available, I would instead check for the existance of the process ID by checking if the directory /proc/$PID existed, but not everyone uses proc anymore. That version is currently the one at http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html but I plan on upgrading to this new version soon. Show Sample Output


    13
    sleeper(){ while `ps -p $1 &>/dev/null`; do echo -n "${2:-.}"; sleep ${3:-1}; done; }; export -f sleeper
    AskApache · 2009-09-21 07:36:25 1
  • The above code is just an example of printing on the same line, hit Ctrl + C to stop When using echo -ne "something\r", echo will: - print "something" - dont print a new line (-n) - interpret \r as carriage return, going back to the start of the line (-e) Remember to print some white spaces after the output if your command will print lines of different sizes, mainly if one line will be smaller than the previous Edit from reading comments: You can achieve the same effect using printf (more standardized than echo): while true; do printf "%-80s\r" "$(date)"; sleep 1; done


    12
    while true; do echo -ne "$(date)\r"; sleep 1; done
    polaco · 2009-11-17 22:45:37 4
  • if you're using wildcards * or ? in your command, and if you're deleting, moving multiple files, it's always safe to see how those wildcards will expand. if you put "echo" in front of your command, the expanded form of your command will be printed. It's better safe than sorry. Show Sample Output


    11
    echo rm *.txt
    alperyilmaz · 2010-10-27 07:26:26 3
  • It will only work if the service NETSEND in the Windows machine is enabled.


    9
    echo "message" | smbclient -M NAME_OF_THE_COMPUTER
    mvrilo · 2010-02-28 21:10:46 0
  • PING parameters c 1 limits to 1 pinging attempt q makes the command quiet (or silent mode) /dev/null 2>&1 is to remove the display && echo ONLINE is executed if previous command is successful (return value 0) || echo OFFLINE is executed otherwise (return value of 1 if unreachable or 2 if you're offline yourself). I personally use this command as an alias with a predefined machine name but there are at least 2 improvements that may be done. Asking for the machine name or IP Escaping the output so that it displays ONLINE in green and OFFLINE in red (for instance).


    9
    ping -c 1 -q MACHINE_IP_OR_NAME >/dev/null 2>&1 && echo ONLINE || echo OFFLINE
    UnixNeko · 2012-02-09 06:30:55 7

  • 8
    echo Print text vertically|sed 's/\(.\)/\1\n/g'
    axelabs · 2009-03-04 23:58:02 6
  • Useful for use in other scripts for renaming, testing for extensions, etc. Show Sample Output


    6
    FILENAME=${FILE##*/};FILEPATH=${FILE%/*};NOEXT=${FILENAME%\.*};EXT=${FILE##*.}
    eduo · 2009-06-10 16:11:38 4
  • Prints out an ascii chart using builtin bash! Then formats using cat -t and column. The best part is: echo -e "${p: -3} \\0$(( $i/64*100 + $i%64/8*10 + $i%8 ))"; From: http://www.askapache.com/linux/ascii-codes-and-reference.html Show Sample Output


    6
    for i in {1..256};do p=" $i";echo -e "${p: -3} \\0$(($i/64*100+$i%64/8*10+$i%8))";done|cat -t|column -c120
    AskApache · 2014-04-04 16:54:53 2
  • The "proportional set size" is probably the closest representation of how much active memory a process is using in the Linux virtual memory stack. This number should also closely represent the %mem found in ps(1), htop(1), and other utilities. Show Sample Output


    5
    echo 0$(awk '/Pss/ {printf "+"$2}' /proc/$PID/smaps)|bc
    atoponce · 2013-09-26 18:20:22 0
  • Like 7171, but fixed typo, uses fewer variables, and even more cryptic! Show Sample Output


    4
    read -a A<<<".*.**..*....*** 8 9 5 10 6 0 2 11 7 4";for C in `date +"%H%M"|fold -w1`;do echo "${A:${A[C+1]}:4}";done
    __ · 2010-12-02 22:04:49 1

  • 4
    color () { local color=39; local bold=0; case $1 in green) color=32;; cyan) color=36;; blue) color=34;; gray) color=37;; darkgrey) color=30;; red) color=31;; esac; if [[ "$2" == "bold" ]]; then bold=1; fi; echo -en "\033[${bold};${color}m"; }
    zvyn · 2013-09-06 09:37:42 0
  • Unlike other methods that use pipes and exec software like tr or sed or subshells, this is an extremely fast way to print a line and will always be able to detect the terminal width or else defaults to 80. It uses bash builtins for printf and echo and works with printf that supports the non-POSIX `-v` option to store result to var instead of printing to stdout. Here it is in a function that lets you change the line character to use and the length with args, it also supports color escape sequences with the echo -e option. function L() { local l=; builtin printf -vl "%${2:-${COLUMNS:-`tput cols 2>&-||echo 80`}}s\n" && echo -e "${l// /${1:-=}}"; } With color: L "`tput setaf 3`=" 1. Use printf to store n space chars followed by a newline to an environment variable "l" where n is local environment variable from $COLUMNS if set, else it will use `tput cols` and if that fails it will default to 80. 2. If printf succeeds then echo `$l` that contains the chars, replacing all blank spaces with "-" (can be changed to anything you want). From: http://www.askapache.com/linux/bash_profile-functions-advanced-shell.html http://www.askapache.com/linux/bash-power-prompt.html Show Sample Output


    4
    printf -vl "%${COLUMNS:-`tput cols 2>&-||echo 80`}s\n" && echo ${l// /-};
    AskApache · 2016-09-25 10:37:20 0
  • Based on the MrMerry one, just add some visuals to differentiate files and directories


    3
    du -a --max-depth=1 | sort -n | cut -d/ -f2 | sed '$d' | while read i; do if [ -f $i ]; then du -h "$i"; else echo "$(du -h --max-depth=0 "$i")/"; fi; done
    nickwe · 2009-09-03 20:43:43 0
  • displays current time in "binary clock" format (loosely) inspired by: http://www.thinkgeek.com/homeoffice/lights/59e0/ "Decoding": 8421 .... - 1st hour digit: 0 *..* - 2nd hour digit: 9 (8+1) .*.. - 1st minutes digit: 4 *..* - 2nd minutes digit: 9 (8+1) Prompt-command version: PROMPT_COMMAND='echo "10 i 2 o $(date +"%H%M"|cut -b 1,2,3,4 --output-delimiter=" ") f"|dc|tac|xargs printf "%04d\n"|tr "01" ".*"' Show Sample Output


    3
    echo "10 i 2 o $(date +"%H%M"|cut -b 1,2,3,4 --output-delimiter=' ') f"|dc|tac|xargs printf "%04d\n"|tr "01" ".*"
    unefunge · 2010-11-24 23:49:21 2
  • This is mostly for my own notes but this command will compute a md5 message digest from the command line. You can also replace md5sum with other checksum commands (e.g., sha1sum) Show Sample Output


    3
    echo -n "password"|md5sum|awk '{print $1}'
    windfold · 2011-11-08 21:34:50 2
  • When you've got a list of numbers each on its row, the ECHO command puts them on a simple line, separated by space. You can then substitute the spaces with an operator. Finally, pipe it to the BC program. Show Sample Output


    2
    echo $( du -sm /var/log/* | cut -f 1 ) | sed 's/ /+/g'
    flux · 2009-07-31 21:42:53 1
  • Based on the MrMerry one, just add some visuals and sort directory and files


    2
    find . -maxdepth 1 -type d|xargs du -a --max-depth=0|sort -rn|cut -d/ -f2|sed '1d'|while read i;do echo "$(du -h --max-depth=0 "$i")/";done;find . -maxdepth 1 -type f|xargs du -a|sort -rn|cut -d/ -f2|sed '$d'|while read i;do du -h "$i";done
    nickwe · 2009-09-03 20:33:21 1
  • Finds executable and existing directories in your path that can be useful if migrating a profile script to another system. This is faster and smaller than any other method due to using only bash builtin commands. See also: + http://www.commandlinefu.com/commands/view/743/list-all-execs-in-path-usefull-for-grepping-the-resulting-list + http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html Show Sample Output


    2
    for p in ${PATH//:/ }; do [[ -d $p && -x $p ]] && echo $p; done
    AskApache · 2009-09-19 06:43:57 1
  • First argument: string to put a box around. Second argument: character to use for box (default is '=') Same as command #4962, cleaned up, shortened, and more efficient. Now a ' * ' can be used as the box character, and the variables get unset so they don't mess with anything else you might have. They marked c++ as a function for this command, but I'm not sure why. Must be a bug. Show Sample Output


    2
    box(){ c=${2-=}; l=$c$c${1//?/$c}$c$c; echo -e "$l\n$c $1 $c\n$l"; unset c l;}
    mightybs · 2010-02-26 17:14:52 0
  • It is helpful to know the current limits placed on your account, and using this shortcut is a quick way to figuring out which values to change for optimization or security. Alias is: alias ulimith="command ulimit -a|sed 's/^.*\([a-z]\))\(.*\)$/-\1\2/;s/^/ulimit /'|tr '\n' ' ';echo" Here's the result of this command: ulimit -c 0 -d unlimited -e 0 -f unlimited -i 155648 -l 32 -m unlimited -n 8192 -p 8 -q 819200 -r 0 -s 10240 -t unlimited -u unlimited -v unlimited -x unlimited ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 155648 max locked memory (kbytes, -l) 32 max memory size (kbytes, -m) unlimited open files (-n) 8192 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 10240 cpu time (seconds, -t) unlimited max user processes (-u) unlimited virtual memory (kbytes, -v) unlimited file locks (-x) unlimited Show Sample Output


    2
    echo "ulimit `ulimit -a|sed -e 's/^.*\([a-z]\))\(.*\)$/-\1\2/'|tr "\n" ' '`"
    AskApache · 2010-03-12 06:46:54 1
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back ssh from firewalled hosts
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Erase a word
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sudo for entire line (including pipes and redirects)
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Find broken symlinks and delete them
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Write comments to your history.
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