From: ZheNing Hu <adlternative@xxxxxxxxx> In the original documentation of `trailer.<token>.command`, some descriptions are easily misunderstood. So let's modify it to increase its readability. In addition, clarify that `$ARG` in command can only be replaced once. Signed-off-by: ZheNing Hu <adlternative@xxxxxxxxx> --- Documentation/git-interpret-trailers.txt | 37 ++++++++++++++---------- 1 file changed, 21 insertions(+), 16 deletions(-) diff --git a/Documentation/git-interpret-trailers.txt b/Documentation/git-interpret-trailers.txt index 96ec6499f001..6f2a7a130464 100644 --- a/Documentation/git-interpret-trailers.txt +++ b/Documentation/git-interpret-trailers.txt @@ -232,25 +232,30 @@ trailer.<token>.ifmissing:: that option for trailers with the specified <token>. trailer.<token>.command:: - This option can be used to specify a shell command that will - be called to automatically add or modify a trailer with the - specified <token>. + This option can be used to specify a shell command that will be called: + once to automatically add a trailer with the specified <token>, and then + each time a '--trailer <token>=<value>' argument to modify the <value> of + the trailer that this option would produce. + -When this option is specified, the behavior is as if a special -'<token>=<value>' argument were added at the beginning of the command -line, where <value> is taken to be the standard output of the -specified command with any leading and trailing whitespace trimmed -off. +When the specified command is first called to add a trailer +with the specified <token>, the behavior is as if a special +'--trailer <token>=<value>' argument was added at the beginning +of the "git interpret-trailers" command, where <value> +is taken to be the standard output of the command with any +leading and trailing whitespace trimmed off. + -If the command contains the `$ARG` string, this string will be -replaced with the <value> part of an existing trailer with the same -<token>, if any, before the command is launched. +If some '--trailer <token>=<value>' arguments are also passed +on the command line, the command is called again once for each +of these arguments with the same <token>. And the <value> part +of these arguments, if any, will be used to replace the first +occurrence of substring `$ARG` in the command. This way the +command can produce a <value> computed from the <value> passed +in the '--trailer <token>=<value>' argument. + -If some '<token>=<value>' arguments are also passed on the command -line, when a 'trailer.<token>.command' is configured, the command will -also be executed for each of these arguments. And the <value> part of -these arguments, if any, will be used to replace the `$ARG` string in -the command. +For consistency, the first occurrence of substring `$ARG` is +also replaced, this time with the empty string, in the command +when the command is first called to add a trailer with the +specified <token>. EXAMPLES -------- -- gitgitgadget
