[Bash] Check the existence of a command

#!/bin/bash # check the existence of a command [ base on the returns of which and alias ] # usage: #           chkcmd.sh command-list # e.g., #           chkcmd.sh pdfit #           http://scriptdemo.blogspot.ca source ~/.bashrc if [ $# -eq 0 ]; then    sed -n '2,6p' `which chkcmd.sh`    exit else    for mycmd in $*    do       isInPath=`which ${mycmd} 2< /dev/null`       if [ ${#isInPath} -eq 0 ]; then          isAlias=`alias ${mycmd} 2< /dev/null`          if [ ${#isAlias} -eq 0 ]; then             echo "${mycmd} is not in the path";          else             echo "${mycmd} is an aliased command";          fi       else          echo "${mycmd} is in the path";       fi    done fi

[Bash] extract pages from a pdf file using gs

#!/bin/bash # extract pages from a big pdf file using gs # Usage: #           pdfselect.sh pdffile startPageNumber endPageNumber #           http://scriptdemo.blogspot.ca function getPDFPages() {    if [ -e $1 ]; then       pdfinfo $1 | grep "Pages" | awk '{print $2}'    else       echo 0;    fi } if [ $# -lt 2 ]; then    sed -n '3,4p' `which pdfselect.sh`    exit fi oriPdf=$1 [ ! -e ${oriPdf} ] && echo "${oriPdf} does not exist! " && exit numPage=`getPDFPages ${oriPdf}` [ ${numPage} -eq 0 ] && "ZERO page is found in ${oriPdf}" && exit sPage=$2 [ ${sPage} -gt ${numPage} ] && ${sPage}=${numPage} if [ $# -eq 2 ]; then    ePage=${sPage} else    ePage=$3; fi [ ${ePage} -gt ${numPage} ] && ${ePage}=${numPage} if [ $# -lt 4 ]; then    outPdf="p${sPage}_${ePage}_${oriPdf}" else    outPdf=$4 fi eval "gs -sDEVICE=pdfwrite -dNOPAUSE -dBATCH -dSAFER -dFirstPage=${sPage} -dLastPage=${ePage} -sOutputFile=${outPdf} ${oriPdf}"

[Matlab] create a time series using datenum

function myT=yymmdd2x(inYear,inMonth,inDay) % create the time axis based on input time [year, mon, date], using datenum % usage: %           xTime=yymmdd2x(years, months, days); % or %           xTime=yymmdd2x(yyyymmdd); %  http://scriptdemo.blogspot.com if (nargin==0 || nargin>3)    help yymmdd2x;    return end if nargin==1    %yyyymmdd case    yyyymmdd=inYear;    inYear=floor(yyyymmdd/10000);    inDay=mod(yyyymmdd,100);    inMonth=floor(mod(yyyymmdd,10000)/100); clear yyyymmdd    totalDaysInYear=datenum(inYear+1,1,1)-datenum(inYear,1,1);    daysInYear=datenum(inYear,inMonth,inDay)-datenum(inYear,1,1)+1;    myT=daysInYear./totalDaysInYear+inYear; elseif nargin==2    % no date, set to 15th, may consider create 12 month for each year if necessary    if length(inYear)~=length(inMonth) && length(inMonth)<=12       % repeat inMonth for each year       inMonth=reshape(inMonth,1,[]);       mm=repmat(inMonth,1,length(inYear));       yy=reshape(repmat(reshape(inYear,1,[]),length(inMonth),1),1,[]);       clear inMonth inYear       totalDaysInYear=datenum(yy+1,1,1)-datenum(yy,1,1);       daysInYearA=datenum(yy,mm+1,1)-datenum(yy,1,1)+1;       daysInYear=datenum(yy,mm,1)-datenum(yy,1,1)+1;       myT=0.5*(daysInYearA+daysInYear)./totalDaysInYear+yy;    elseif (length(inYear)==length(inMonth))       totalDaysInYear=datenum(inYear+1,1,1)-datenum(inYear,1,1);       daysInYearA=datenum(inYear,inMonth+1,1)-datenum(inYear,1,1)+1;       daysInYear=datenum(inYear,inMonth,1)-datenum(inYear,1,1)+1;       myT=0.5*(daysInYearA+daysInYear)./totalDaysInYear+inYear;    else        disp('Too difficult for me to guess what your wanna to do...')        return    end else    totalDaysInYear=datenum(inYear+1,1,1)-datenum(inYear,1,1);    daysInYear=datenum(inYear,inMonth,inDay)-datenum(inYear,1,1)+1;    myT=daysInYear./totalDaysInYear+inYear; end