From 703037eb0880d4acf25af9e108f56e98e16d33ed Mon Sep 17 00:00:00 2001 From: cem Date: Sat, 4 Mar 2017 22:38:10 +0000 Subject: [PATCH] ps(1): Only detect terminal width if stdout is a tty If stdout isn't a tty, use unlimited width output rather than truncating to 79 characters. This is helpful for shell scripts or e.g., 'ps | grep foo'. This hardcoded width has some history: In The Beginning of History[0], the width of ps was hardcoded as 80 bytes. In 1985, Bloom@ added detection using TIOCGWINSZ on stdin.[1] In 1986, Kirk merged a change to check stdout's window size instead. In 1990, the fallback checks to stderr and stdin's TIOCGWINSZ were added by Marc@, with the commit message "new version."[2] OS X Darwin has a very similar modification to ps(1), which simply sets UNLIMITED for all non-tty outputs.[3] I've chosen to respect COLUMNS instead of behaving identically to Darwin here, but I don't feel strongly about that. We could match OS X for parity if that is desired. [0]: https://svnweb.freebsd.org/csrg/bin/ps/ps.c?annotate=1065 [1]: https://svnweb.freebsd.org/csrg/bin/ps/ps.c?r1=18105&r2=18106 [2]: https://svnweb.freebsd.org/csrg/bin/ps/ps.c?r1=40675&r2=40674&pathrev=40675 [3]: https://opensource.apple.com/source/adv_cmds/adv_cmds-168/ps/ps.c.auto.html PR: 217159 Reported by: Deepak Nagaraj --- bin/ps/ps.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/bin/ps/ps.c b/bin/ps/ps.c index 12a6f81c99ad..4fb0be9722ca 100644 --- a/bin/ps/ps.c +++ b/bin/ps/ps.c @@ -194,6 +194,8 @@ main(int argc, char *argv[]) if ((cols = getenv("COLUMNS")) != NULL && *cols != '\0') termwidth = atoi(cols); + else if (!isatty(STDOUT_FILENO)) + termwidth = UNLIMITED; else if ((ioctl(STDOUT_FILENO, TIOCGWINSZ, (char *)&ws) == -1 && ioctl(STDERR_FILENO, TIOCGWINSZ, (char *)&ws) == -1 && ioctl(STDIN_FILENO, TIOCGWINSZ, (char *)&ws) == -1) ||