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x/term: Why IsTerminal reports true on redirected stdout? [unrelated] #42003

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gabyx opened this issue Oct 15, 2020 · 7 comments
Closed

x/term: Why IsTerminal reports true on redirected stdout? [unrelated] #42003

gabyx opened this issue Oct 15, 2020 · 7 comments
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FrozenDueToAge WaitingForInfo Issue is not actionable because of missing required information, which needs to be provided.
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Unreleased

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@gabyx
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gabyx commented Oct 15, 2020 •
edited

What version of Go are you using (go version)?

1.15.2

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output
$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/gabyx/Library/Caches/go-build"
GOENV="/Users/gabyx/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/gabyx/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/gabyx/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/Cellar/go/1.15.2/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.15.2/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/gabyx/Desktop/githooks/githooks/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/jf/0dqq5t6x0rxd9kkp8vmc18gc0000gn/T/go-build702825481=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

package main

import (
	"fmt"
	"golang.org/x/term"
	"os"
)

func main() {
    if term.IsTerminal(int(os.Stdout.Fd())) {
        fmt.Println("Is Terminal")
    }
}

and run it with ./run 1> Log.txt.

What did you expect to see?

No output in Log.txt because stdout is redirected?

What did you see instead?

Is Terminal in Log.txt
@gopherbot gopherbot added this to the Unreleased milestone Oct 15, 2020
@ianlancetaylor
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Your program doesn't compile:

foo.go:10:33: cannot use os.Stdout.Fd() (type uintptr) as type int in argument to term.IsTerminal

When I fix that, the program behaves as I expect:

> ./foo
Is Terminal
> ./foo > /tmp/x.txt
> cat /tmp/x.txt
>

Show us a way to reproduce the problem.

@ianlancetaylor ianlancetaylor added the WaitingForInfo Issue is not actionable because of missing required information, which needs to be provided. label Oct 15, 2020
@gabyx
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gabyx commented Oct 16, 2020

Updated

@gabyx
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gabyx commented Oct 16, 2020

Really. I am on Darwin macOs in a Zsh shell. There it happens.

@gabyx
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gabyx commented Oct 16, 2020

I will provide more infos!

@davecheney
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@gabyx I am using darwin with zsh, I cannot reproduce your findings

(~/src) % go build term.go && ./term | tee log.out
(~/src) % cat log.out
(~/src) % go build term.go && ./term > log.out
(~/src) % cat log.out
(~/src) %

@gabyx
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gabyx commented Oct 16, 2020 via email

@gabyx
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gabyx commented Oct 18, 2020 •
edited

Sorry for your precious time. I mistakenly used the compiled code under a hook invoked by git commit which is where I got confused -> git attaches its stderr to both stdout/stderr of the hook executable... hm...

This works fine.

@gabyx gabyx closed this as completed Oct 18, 2020
@gabyx gabyx changed the title x/term: Why IsTerminal reports true on redirected stdout? x/term: Why IsTerminal reports true on redirected stdout? [unrelated] Oct 18, 2020
@golang golang locked and limited conversation to collaborators Oct 18, 2021
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@davecheney @gabyx @ianlancetaylor @gopherbot