Create a function in a bash shell or script:
color()(set -o pipefail;"$@" 2>&1>&3|sed $'s,.*,e[31m&e[m,'>&2)3>&1
Use it like this:
$ color command -program -args
It will show the command's stderr in red.
Keep reading for an explanation of how it works. There are some interesting features demonstrated by this command.
color()... — Creates a bash function called color.set -o pipefail — This is a shell option that preserves the error return code of a command whose output is piped into another command. This is done in a subshell, which is created by the parentheses, so as not to change the pipefail option in the outer shell. "$@" — Executes the arguments to the function as a new command. "$@" is equivalent to "$1" "$2" ...2>&1 — Redirects the stderr of the command to stdout so that it becomes sed's stdin.>&3 — Shorthand for 1>&3, this redirects stdout to a new temporary file descriptor 3. 3 gets routed back into stdout later.sed ... — Because of the redirects above, sed's stdin is the stderr of the executed command. Its function is to surround each line with color codes.$'...' A bash construct that causes it to understand backslash-escaped characters.* — Matches the entire line.e[31m — The ANSI escape sequence that causes the following characters to be red& — The sed replace character that expands to the entire matched string (the entire line in this case).e[m — The ANSI escape sequence that resets the color.>&2 — Shorthand for 1>&2, this redirects sed's stdout to stderr.3>&1 — Redirects the temporary file descriptor 3 back into stdout.
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
