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authorIndrajith K L2022-12-03 17:00:20 +0530
committerIndrajith K L2022-12-03 17:00:20 +0530
commitf5c4671bfbad96bf346bd7e9a21fc4317b4959df (patch)
tree2764fc62da58f2ba8da7ed341643fc359873142f /v_windows/v/examples/process/process_stdin_trick.v
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Adds most of the toolsHEADmaster
Diffstat (limited to 'v_windows/v/examples/process/process_stdin_trick.v')
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diff --git a/v_windows/v/examples/process/process_stdin_trick.v b/v_windows/v/examples/process/process_stdin_trick.v
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+module main
+
+import os
+
+// this is a example script to show you stdin can be used and keep a process open
+
+fn exec(cmd string) (string, int) {
+ mut cmd2 := cmd
+ mut out := ''
+ mut line := ''
+ mut rc := 0
+ mut p := os.new_process('/bin/bash')
+
+ // there are methods missing to know if stderr/stdout has data as such its better to redirect bot on same FD
+ // not so nice trick to run bash in bash and redirect stderr, maybe someone has a better solution
+ p.set_args(['-c', 'bash 2>&1'])
+ p.set_redirect_stdio()
+ p.run()
+
+ if !cmd2.ends_with('\n') {
+ cmd2 += '\n'
+ }
+
+ p.stdin_write(cmd2)
+ p.stdin_write('\necho **OK**\n')
+
+ for {
+ if !p.is_alive() {
+ break
+ }
+ line = p.stdout_read()
+ println(line)
+ // line_err = p.stderr_read() //IF WE CALL STDERR_READ will block
+ // we need a mechanism which allows us to check if stderr/stdout has data or it should never block
+ // is not a good way, need to use a string buffer, is slow like this
+ out += line
+ if out.ends_with('**OK**\n') {
+ out = out[0..(out.len - 7)]
+ break
+ }
+ }
+
+ // println("read from stdout, should not block")
+ // is not really needed but good test to see behaviour
+ // out += p.stdout_read()
+ // println("read done")
+
+ // println(cmd.stderr_read())
+
+ if p.code > 0 {
+ rc = 1
+ println('ERROR:')
+ println(cmd2)
+ print(out)
+ }
+ // documentation says we need to call p.wait(), but this does not seem to work, will be process stop or become zombie?
+ // p.wait()
+
+ return out, rc
+}
+
+fn main() {
+ mut out := ''
+ mut rc := 0
+
+ // the following does not work, not sure why not
+ // out,rc = exec("find /tmp/ && echo '******'")
+
+ out, rc = exec("find /tmp/ ; echo '******'")
+ println(out)
+ assert out.ends_with('******\n')
+
+ out, rc = exec('echo to stdout')
+ assert out.contains('to stdout')
+
+ out, rc = exec('echo to stderr 1>&2')
+ assert out.contains('to stderr')
+
+ out, rc = exec('ls /sssss')
+ assert rc > 0 // THIS STILL GIVES AN ERROR !
+
+ println('test ok stderr & stdout is indeed redirected')
+}