Commands using unset (14)

  • this will cause any commands that you have executed in the current shell session to not be written in your bash_history file upon logout


    17
    unset HISTFILE
    syssyphus · 2009-05-20 14:46:18 4
  • Unset TMOUT or set it to 0 in order to prevent shell autologout. TMOUT is the number of seconds after which the present shell will be killed if it has been idle for that long.


    7
    unset TMOUT
    sharfah · 2009-05-20 14:57:50 5
  • Unsetting HISTFILE avoid getting current session history list saved.


    6
    unset HISTFILE
    Delian · 2010-11-15 09:16:11 3
  • works on all unices. Show Sample Output


    4
    function nowrap { export COLS=`tput cols` ; cut -c-$COLS ; unset COLS ; }
    mobidyc · 2009-09-11 15:07:00 6
  • Simply sourcing .bashrc does not function correctly when you edit it and change an alias for a function or the other way round with the *same name*. I therefor use this function. Prior to re-sourcing .bashrc it unsets all aliases and functions.


    4
    bashrc-reload() { builtin unalias -a; builtin unset -f $(builtin declare -F | sed 's/^.*declare[[:blank:]]\+-f[[:blank:]]\+//'); . ~/.bashrc; }
    Xk2c · 2014-03-02 14:24:18 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
  • pushd and popd are your friends, but sometimes they're just incompatible with the way one works... Two shell functions: bm bookmarkname - "bookmarks" the current directory, just 'cd $BMbookmarkname' to return to it. forget bookmarkname - unsets the 'bookmarkname' variable. It isn't mandatory, they cease to exist when the session ends. Show Sample Output


    2
    bm() { export BM${1?"bookmark name missing"}="$PWD" ; }; forget() { unset BM${1?"bookmark name missing"} ; }
    unefunge · 2010-11-19 12:15:11 0

  • 1
    MYSQL="mysql -h HOST -u USERNAME -pPASSWORD -D DB_NAME" ; $MYSQL -BNe "show tables" | awk '{print "set foreign_key_checks=0; drop table `" $1 "`;"}' | $MYSQL unset MYSQL
    gadget00 · 2009-12-01 17:42:38 3
  • make, find and a lot of other programs can take a lot of time. And can do not. Supppose you write a long, complicated command and wonder if it will be done in 3 seconds or 20 minutes. Just add "R" (without quotes) suffix to it and you can do other things: zsh will inform you when you can see the results. You can replace zenity with other X Window dialogs program.


    1
    alias -g R=' &; jobs | tail -1 | read A0 A1 A2 cmd; echo "running $cmd"; fg "$cmd"; zenity --info --text "$cmd done"; unset A0 A1 A2 cmd'
    pipeliner · 2010-12-13 17:44:36 0

  • 1
    echo 'set term dumb; unset border; unset xtics; unset ytics; p "< seq 10 | shuf" u 1:(rand(0)) w l notitle' | gnuplot
    kev · 2011-11-30 02:08:53 0
  • unsets variables used by the one-liner sets up the IFS bash variable to not be affected by whitespace and disables extra glob expansion uses read to slurp the results of the find command into an array selects an element of the array at random to be passed as an argument to mplayer


    0
    unset files i; set -f; O=$IFS; while IFS= read -r -d $'\0' files[i++]; do :; done < <(find . -name '*.avi' -print0) && IFS=$O; set +f && echo "Running: mplayer \"${files[ $(( $RANDOM % ${#files[@]} )) ]}\""
    DEinspanjer · 2009-02-18 16:53:57 1
  • If I type 'man something', I want it to find the manpage in the same order as my PATH. You can add something like this to your .bashrc # # Add my MacPorts, my personal utilities and my company utilities to my PATH. export PATH=$PATH:/opt/local/bin:$HOME/bin:/our_company_utils/bin/ # Now set the manpath based on the PATH, after man(1) parses man.conf # - No need to modify man.conf or manually modify MANPATH_MAP # - Works on Linux, FreeBSD & Darwin, unlike /etc/manpaths.d/ # Must unset MANPATH first. MANPATH is set on some systems automatically (Mac), # which causes manpath to ignore the values of PATH like /opt/local/bin (MacPorts). # Also MANPATH may be deprecated. See "SEARCH PATH FOR MANUAL PAGES" in man(1) unset MANPATH # manpath acts differently on Solaris, FreeBSD, MacOSX & GNU. This works everywhere. manpath >/dev/null # Note that MacOSX, FreeBSD & Linux have fancier ways to do some of this. (e.g. 'man --path' or 'man -q'), but this command is more universal and should work everywhere. Show Sample Output


    0
    unset MANPATH; manpath >/dev/null
    StefanLasiewski · 2010-07-02 19:45:27 0
  • The given file may contain any kind of characters. This is compatible for most simple mathematical operation. For the first number found, it will be replaced by the result of a factor operation of 1000. To change the filename or multiplactor or number regular expression, change the first fixed values. Show Sample Output


    0
    n=1000;f="test.csv";r='([0-9]+.{0,1}[0-9]*)';echo -n "" > new_${f};cat $f | while read l;do val=`echo $l | egrep -o $r` ; if [ ! -z $val ];then newval=`echo $val \* $n | bc -l`;l=`echo $l | sed "s/$val/$newval/"`;fi;echo $l >> new_${f};unset val;done
    s333 · 2017-04-26 18:04:07 0

  • 0
    unset HISTFILE
    aysadk · 2017-09-01 09:12:11 0

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Show errors in the kernel ring buffer
Much more useful then parsing syslog

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" }

Pulse Volume Control Using Zenity
This produces a little bar that you can use to set the volume percentage.

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" }

Create a persistent connection to a machine
Create a persistent SSH connection to the host in the background. Combine this with settings in your ~/.ssh/config: Host host ControlPath ~/.ssh/master-%r@%h:%p ControlMaster no All the SSH connections to the machine will then go through the persisten SSH socket. This is very useful if you are using SSH to synchronize files (using rsync/sftp/cvs/svn) on a regular basis because it won't create a new socket each time to open an ssh connection.

list files in mtime order
Simple but useful; list files in the current directory in mtime order. Useful if you've been working on something and then take a day or two off.

convert unixtime to human-readable

Convert your favorite image in xpm for using in grub
* size must be 640?480 pixels * only has 14 colors * save it in XPM format Edit /boot/grub/menu.lst and add splashimage=(hd0,0)/boot/grub/grubimg.xpm make sure for your path name and hard disk

Buffer in order to avoir mistakes with redirections that empty your files
A common mistake in Bash is to write command-line where there's command a reading a file and whose result is redirected to that file. It can be easily avoided because of : 1) warnings "-bash: file.txt: cannot overwrite existing file" 2) options (often "-i") that let the command directly modify the file but I like to have that small function that does the trick by waiting for the first command to end before trying to write into the file. Lots of things could probably done in a better way, if you know one...

Quick network status of machine
credit to tumblr engineering blog @ http://engineering.tumblr.com/


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