I'm writing a wrapper around ack
to search for code locally with some additional lines of context piped to a pager.
Here's the wrapper script ackc
. Between the different examples, I'll be varying what gets passed to ack
as the --pager
.
#!/bin/sh
ack -C 20 -i \
--pager=most \
--heading \
--break \
--color \
--show-types \
"$@"
With less
(without the -R) as the pager, almost all of the escape sequences are rendered using the caret notation (don't know what that's called. ^[
is the exception. It is rendered as ESC
with inverted background colors (colors not reproduced here).
Here's a sample of the output (produced by ackc
with --pager=less
and environment variables such as LESS
, LESSPIPE
etc cleared)
ESC[1;32m.local/lib/python2.7/site-packages/markupsafe/_speedups.cESC[0m
...
ESC[1;33m19ESC[0m:#define PY_SSIZE_T_MAX ESC[30;43mINTESC[0m_MAXESC[0mESC[K
ESC[1;33m20ESC[0m:#define PY_SSIZE_T_MIN ESC[30;43mINTESC[0m_MINESC[0mESC[K
The important escape sequence here is the ^[[K
sequence at the end of each line containing a highlighted item. It is handled appropriately by less -R
.
.local/lib/python2.7/site-packages/markupsafe/_speedups.c
...
19:#define PY_SSIZE_T_MAX INT_MAX
20:#define PY_SSIZE_T_MIN INT_MIN
most
, however, does not seem to handle it very well.
.local/lib/python2.7/site-packages/markupsafe/_speedups.c
1-/**
...
19:#define PY_SSIZE_T_MAX INT_MAX^[[K
20:#define PY_SSIZE_T_MIN INT_MIN^[[K
It passes through the ^[[K
sequence as-is.
This sequence is CSI (n) K -- EL -- Erase in Line
. When given no argument, it erases to the end of the line. Presumably this is needed to clear stray bits of background color if the matched term appears at the end of the line.
Is there a reason why most
doesn't understand this sequence? Can I configure it to process it correctly?
TERM
environment variable?tmux
underlxterminal
, which sets theTERM
environment variable toscreen
. It also happens if I run the command not undertmux
, in which caseTERM
isxterm
.^[[K
to thatmost
will understand? It might be possible to extendack
to emit different escape sequences so it can cooperate with different pagers.