OpenEuphoria

build_commandline

include cmdline.e 
default namespace is cmdline 
public function build_commandline(sequence cmds) 

Returns a text string based on the set of supplied strings.

Parameters:

1. cmds : A sequence. Contains zero or more strings.

Returns:

A sequence, which is a text string. Each of the strings in cmds is quoted if they contain spaces, and then concatenated to form a single string.

Example 1:

include std/cmdline.e 
include std/filesys.e -- for required canonical_path function 
include std/console.e -- for display function 
 
object s = build_commandline({"-d", canonical_path("/usr/my docs/",,TO_SHORT)}) 
display(s) 
 

Result:

-d "/usr/my docs/" 

Example 2:

You can use this to run things that might be difficult to quote out. Suppose you want to run a program that requires quotes on its command line? Use this function to pass quotation marks:

include std/cmdline.e 
include std/filesys.e -- for required canonical_path function 
include std/console.e -- for display function 
 
object s = build_commandline({"grep","-n","Hello World","*.ex"}) 
display(s)  
system(s,0) 

Results:

grep "Hello World" *.ex 
hello.ex:3:puts(1,"Hello World!\n") 
... 

Comments:

Typically, this is used to ensure that arguments on a command line are properly formed before submitting it to the shell.

Though this function does the quoting for you it is not going to protect your programs from globing *, ? . And it is not specified here what happens if you pass redirection or piping characters.

When passing a result from with build_commandline to system_exec, file arguments will benefit from using canonical_path with the TO_SHORT. On Windows this is required for file arguments to always work. There is a complication with files that contain spaces. On Unix this call will also return a useable filename.

Alternatively, you can leave out calls to canonical_path and use system instead.

See Also:

parse_commandline, system, system_exec, command_line, canonical_path, TO_SHORT