Shell Scripting and Piping

Syntax#

;shell command

Using Shell from inside the REPL

From inside the interative Julia shell (also known as REPL), you can access the system’s shell by typing ; right after the prompt:

shell>

From here on, you can type any shell comand and they will be run from inside the REPL:

shell> ls
Desktop     Documents   Pictures   Templates
Downloads   Music       Public     Videos

To exit this mode, type backspace when the prompt is empty.

Shelling out from Julia code

Julia code can create, manipulate, and execute command literals, which execute in the OS’s system environment. This is powerful but often makes programs less portable.

A command literal can be created using the “ literal. Information can be interpolated using the $ interpolation syntax, as with string literals. Julia variables passed through command literals need not be escaped first; they are not actually passed to the shell, but rather directly to the kernel. However, Julia displays these objects so that they appear properly escaped.

julia> msg = "a commit message"
"a commit message"

julia> command = `git commit -am $msg`
`git commit -am 'a commit message'`

julia> cd("/directory/where/there/are/unstaged/changes")

julia> run(command)
[master (root-commit) 0945387] add a
 4 files changed, 1 insertion(+)