BASH SCRIPT TIPS. function jumpto { label=$1 cmd=$(sed -n "/$label:/{:a;n;p;ba};" $0 grep -v ':$') eval "$cmd" exit }

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Gilbert Hines
5 years ago
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1 BASH SCRIPT TIPS Is user in the dialout group? Is there a goto in bash scripting? cat /etc/group grep dialout grep $USER if [ $R = "0" ] echo "$USER is in the dialout group" sudo adduser $USER dialout echo "$USER has been added to the dialout group" # Dene a "jumpto" function function jumpto { label=$1 cmd=$(sed -n "/$label:/{:a;n;p;ba};" $0 grep -v ':$') eval "$cmd" exit } jumpto startup How do I know what version of Linux I m running? startup: cat /etc/os-release NAME="Linux Mint" VERSION="18.1 (Serena)" ID=linuxmint ID_LIKE=ubuntu PRETTY_NAME="Linux Mint 18.1" VERSION_ID="18.1" HOME_URL=" SUPPORT_URL=" BUG_REPORT_URL=" VERSION_CODENAME=serena UBUNTU_CODENAME=xenial env grep VERSION VTE_VERSION=4205 CINNAMON_VERSION=3.2.7

2 ~ $ cat /etc/issue.net Linux Mint 18.1 Serena How do I get pavucontrol for setting my audio levels? How do I get the output from a web site such as sourceforge.net for fldigi How do I sort a list so that only unique names are listed? How do I fetch the le using the full path? How do I keep just the part of the name after the last slash? How do I take off the tar.gz sufx? How do I extract the contents of a tar.gz le? How do I change to that directory? How do I save all but the last character? How do I know how much memory I have left? How do I nd out what network connections I have? How do I show my WiFi connections? uname -a Linux ron-xps generic #83-Ubuntu SMP Wed Jan 18 14:10:15 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux sudo apt-get install pavucontrol # Install pavucontrol for audio wget -q sourceforge.net/projects/fldigi/les/$i/ >get-list.out cat get-list.out sort -u <get-list.txt >getlist.txt gzname= fltk.org/pub/fltk/1.3.4/fltk source.tar.gz wget $gzname &>/dev/null wrd=${gzname##*/} len=${#word} neword=${wrd:0:$len-7} tar xzf fltk source.tar.gz cd $neword # retain part after last slash wrd=${word:0:$len-1} # Save all but the last character ronh@ron-xps /etc $ free (shown in kilobytes) total used free shared buff/cache available Mem: Swap: Ifcong Output can include en0, eth0, enp3s0, etc. depending on kernel version ifcong grep wlan ifcong grep wlp iwlist $WLAN scanning WLAN = name found, e.g. wlan0 on older kernels and wlp on newer Linux kernels e.g. wlp5s0

3 How much space is left on my hard drives? How do I use a case statement? How do I know if a command succeeded? How do I nd out the current K- index and solar flux? ronh@ron-xps /etc $ df -h (-h means human-readable) Filesystem Size Used Avail Use% Mounted on udev 16G 0 16G 0% /dev tmpfs 3.2G 18M 3.2G 1% /run /dev/sdb4 64G 38G 23G 63% / tmpfs 16G 848K 16G 1% /dev/shm tmpfs 5.0M 4.0K 5.0M 1% /run/lock tmpfs 16G 0 16G 0% /sys/fs/cgroup cgmfs 100K 0 100K 0% /run/cgmanager/fs tmpfs 3.2G 24K 3.2G 1% /run/user/1000 /dev/sde1 121G 90G 31G 75% /media/ronh/gb128 /dev/sda1 1.4T 147G 1.2T 11% /media/ronh/gb1400 /dev/sda2 489G 4.5G 484G 1% /media/ronh/gb500 /dev/sdb5 164G 118G 38G 76% /media/ronh/cd7e099b-f99b-4388-b09fcff3fb05540e echo "$f4" grep tar.gz >/dev/null case $R in 0 ) word=$f4 ;; default ) word=$f5 ;; esac wget $gzname &>/dev/null # Fetch the le # Get the result of the wget command if [ $R = "0" ] echo "" echo "Unable to fetch $gzname - ABORTING" jumpto doabort # wget -np grep Solar flux wwv.txt grep K-index wwv.txt These are just some of things I ve learned along the way writing scripts for fldigi installs, setting up a weather server at home, creating html pages from a script, etc. Most were learned by googling what I wanted to do, trying the various examples.

4 For example, to create a web page in a shell script, this is how I generate the html page for my weather server: # makehtml # Reads readings.txt and produces readings.htm # TGT="readings.htm" SRC="readings.txt" LINE=1 echo "<html><head><title>wx READINGS</title>">$TGT echo "<META HTTP-EQUIV=\"Refresh\" CONTENT=\"60\"">>$TGT echo "</head>">>$tgt echo "<body bgcolor=palegreen>">>$tgt echo "<table border=4>">>$tgt echo "<tr><td>">>$tgt echo "<font size=4>">>$tgt cat $SRC while read f1 f2 f3 f4 f5 f6 f7 f8 f9 f10 do # This is the title at the top of the page # This causes the page to refresh every 60 seconds # make the body background color a palegreen # start a table # start a row and data entry # Set the font size # read the source and put it in the page if [ $LINE -eq 1 ] echo -n "<b>">>$tgt echo "$f1 $f2 $f3 $f4 $f5 $f6 $f7 $f8 $f9 $f10 <hr>">>$tgt echo "</b>">>$tgt LINE=0 echo "$f1 $f2 $f3 $f4 $f5 $f6 $f7 $f8 $f9 $f10<br>">>$tgt done echo "</td></tr>">>$tgt # Close the data and row echo "<tr><td align=center>">>$tgt # next table data is centered echo "<font size=2>">>$tgt # set font size to 2 echo "Readings are updated <br>automatically every 5 minutes at DM42ji</td>">>$TGT #close the table data echo "</tr>">>$tgt # close the row echo "</table>">>$tgt # close the table echo "</body></html>">>$tgt # end the html page Sometimes, a shell script can only do so much, or it would take an inordinate amount of time to create. Then I revert to the C language. Having used C since about 1977, I do a lot of my programming in C just because it is fast and easy for me. A plus is the fact that most Linux distributions have a C compiler built in to them. I learned C and Unix from the guys at Bell Labs when I was working for Pacic Northwest Bell as a senior analyst and troubleshooter for their Electronic Switching Systems. Back we used a DEC PDP-7 and PDP-45. Now that is nostalgic :-)

5 Hopefully you will nd these useful. They will also be appearing in the April SIG newsletter. Ron W7HD

UNIVERSITY OF BOLTON CREATIVE TECHNOLOGIES COMPUTING WITH WEBSITE DEVELOPMENT SEMESTER ONE EXAMINATIONS 2018/2019 UNIX MODULE NO: CPU5003

[CRT08] UNIVERSITY OF BOLTON CREATIVE TECHNOLOGIES COMPUTING WITH WEBSITE DEVELOPMENT SEMESTER ONE EXAMINATIONS 2018/2019 UNIX MODULE NO: CPU5003 Date: Wednesday 16 th January 2019 Time: 10:00 12:00 INSTRUCTIONS