What I learned today

Simply put, using the bash for loop and other standard commands it can be a quite powerful method to write custom content to files/databases etc For example #!/bin/bash list=$(cat somefile | grep jar | sed 's/aaa/bbb/g') # add each of the paths as a system scope dependency to the pom counter=1 for OUTPUT in $list do         pathvar=/$OUTPUT         echo "          <dependency>             <groupId>x</groupId>             <artifactId>$counter</artifactId>             <version>1.0</version>             <systemPath>$pathvar</systemPath>             <scope>system</scope>          </dependency>         " >> pom.xml  ...

I recently had to develop a bash script in order to automate the submission of a job The job submission script could be run like this someTextOutput | thatCommand So 'thatCommand' can be piped input directly. My issue was that 'someTextOutput' for me needed to be template replaced with user provided inputs. For example I wanted to do this % aCommand var1 var2 This should replace values of tokens in a template file with var1 and var2 and the resulting output should become 'someTextOutput' I discovered the m4 template processor tool, and here was my solution, or close to it. Cool! #!/bin/bash # some input handling code ... # now send over template processed output to the target command cat /tmp/templateFile.txt | m4 -Dvar1="$1" -Dvar2="$2" | thatCommand I can use this in so many applications, all without having to resort to other tools/scripts when I don't need to. Happy scripting!