英文:
Is it possible to detect if a writer is tty or not?
问题
Bash有一个"神奇的行为"，如果你输入'ls'，通常会得到彩色的输出，但如果你将输出重定向到文件，颜色代码就会消失。如何使用Go实现这种效果。例如，使用以下语句：
fmt.Println("3[1;34mHello World!3[0m")
我可以看到有颜色的文本，但如果我将输出导入到文件中，颜色是被保留的，这不是我想要的效果。
顺便说一下，这个问题大部分与Go无关，我只是想在我的Go程序中实现这种效果。
英文:
Bash has a 'magical behavior', if you type 'ls', usually you will get colorful output, but if you redirect the output to a file, the color codes are gone. How to achive this effect using Go. e.g. With the following statement:
fmt.Println("3[1;34mHello World!3[0m")
I can see the text in color, but if I pipe the output to a file, the color is preserved, which is NOT what I want.
BTW, this question is mostly not related to Go, I just want to achive the effect in my go program.
答案1
得分: 6
Bash有一个"神奇的行为"，如果你输入"ls"，通常会得到彩色的输出，但如果你将输出重定向到文件，颜色代码就会消失。
这不是Bash的特性，而是ls的特性。它调用isatty()来检查stdout文件描述符是否指向终端。在musl libc中，isatty的实现如下：
int isatty(int fd)
{
struct winsize wsz;
unsigned long r = syscall(SYS_ioctl, fd, TIOCGWINSZ, &wsz);
if (r == 0) return 1;
if (errno != EBADF) errno = ENOTTY;
return 0;
}
你可以在Go中使用相同的方法：
package main
import (
"fmt"
"os"
"golang.org/x/sys/unix"
)
func main() {
_, err := unix.IoctlGetWinsize(int(os.Stdout.Fd()), unix.TIOCGWINSZ)
if err != nil {
fmt.Println("Hello World")
} else {
fmt.Println("3[1;34mHello World!3[0m")
}
}
英文:
> Bash has a 'magical behavior', if you type 'ls', usually you will
get colorful output, but if you redirect the output to a file, the
color codes are gone.
It's not Bash feature, it's ls feature. It calls
isatty()
to check if stdout file descriptor refers to a terminal. In musl libc
isatty is implemented like that:
int isatty(int fd)
{
struct winsize wsz;
unsigned long r = syscall(SYS_ioctl, fd, TIOCGWINSZ, &wsz);
if (r == 0) return 1;
if (errno != EBADF) errno = ENOTTY;
return 0;
}
You can use the same method in Go:
package main
import (
"fmt"
"os"
"golang.org/x/sys/unix"
)
func main() {
_, err := unix.IoctlGetWinsize(int(os.Stdout.Fd()), unix.TIOCGWINSZ)
if err != nil {
fmt.Println("Hello World")
} else {
fmt.Println("3[1;34mHello World!3[0m")
}
}
答案2
得分: 3
我只是复制了@ptx的评论作为回答，这是更标准的答案：
> 更好的方法是使用x/term中的term.IsTerminal。它适用于Windows，并由golang团队维护。
这样做是为了提高可见性，因为这个答案是可移植的，不会增加外部依赖。
package main
import (
"os"
"golang.org/x/term"
)
func main() {
if term.IsTerminal(int(os.Stdout.Fd())) {
// 当我们连接到tty时执行某些操作
} else {
// 当我们没有连接时执行某些操作
}
}
英文:
I'm just answering by copying @ptx comment, which is the more canonical answer:
> A better approach is to use term.IsTerminal from x/term. It works on windows and is maintained by the golang team
This is to raise visibility, as this answer is portable and doesn't add an external dependency.
package main
import (
"os"
"golang.org/x/term"
)
func main() {
if term.IsTerminal(int(os.Stdout.Fd())) {
// do stuff when we are attached to a tty
} else {
// do stuff when we are not attached
}
}
答案3
得分: 0
如果你只是查看日志文件，并且不希望保留颜色，因为这会使日志变得不易读，请注意以下命令：
less -r logfile
more -r logfile
multitail -cT ANSI logfile
这些命令将显示 ANSI 颜色。
还有一个 vim 插件可以实现相同的效果：https://github.com/powerman/vim-plugin-AnsiEsc
对于某些用例而言，这可能是一个比升级应用程序以检测输出是否连接到 tty 更简单的解决方案。
英文:
If you are just viewing a log file and don't want colors being preserved because it makes logs less readable, note that
less -r logfile
more -r logfile
multitail -cT ANSI logfile
will make these commands display ANSI colors.
There is also a vim plugin which does the same: https://github.com/powerman/vim-plugin-AnsiEsc
For some use cases this could be a simpler solution than upgrading an app to detect whether an output is attached to a tty.
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