Some bash script tips

Every morning do a refresh of all my repositories so that I know I don’t fall behind on the code if I need to solve some problem or continue developing. Doing this manually is not practical, and so I created a bash script to refresh all my repositories. While I was at it I added a starting command for the apache and mysql. Since I do not desire to start them if they are already running, the script check first if they are already running. Writing this script I learned a lot about shell scripting. Here are some of the things I picked up

Adding -x to the shebang will make bash output everything that is going on, helps with debugging

Giving a variable as a parameter to a function, if you just give the variable name it will be treated as a string value and that will be passed to the function. I ended up encapsulating it as "${var}" since the value was a string. If your value is not a string you probably need some other solution.

Comparing a variable to a string is best achieved with the following syntax: if[ "${var}" = "foo" ]; then Notice the space between the brackets and the values inside.

Using grep to pick something out of a list of processes requires an extra step in which you remove the grep itself from the list. ps -e | grep -v grep | grep searchstring Otherwise grep might find its own search process, which is of course not the desired effect.

Hopefully this will save you some time in scripting.