Package: less
Version: 394-1
Severity: normal
Piping data to less makes the command pause, as shown with the
following test case.
---- lessbuffbug -------------------------------------------------
#!/bin/bash
[[ -c "$1" ]] || { echo "Usage: lessbuffbug <tty>" >&2; exit 1; }
for (( i=0; i<30000; i++ ))
do
printf "Line.... %6d\n" $i
((i%10)) || echo "Line $i" > "$1"
done
------------------------------------------------------------------
To use it, open two terminals and type in the first one:
./lessbuffbug <tty> | less
where <tty> is the tty file of the second terminal (given by the
"tty" command), and wait a few seconds. The data displayed in the
second terminal stop at some line from "Line 4160" to "Line 4600",
showing the lessbuffbug command has paused. Typing spaces in less
leads to more data displyed in the other terminal.
According to the documentation, this behavior is incorrect:
-B or --auto-buffers
By default, when data is read from a pipe, buffers are
allocated automatically as needed. If a large amount of
data is read from the pipe, this can cause a large amount
of memory to be allocated. The -B option disables this
automatic allocation of buffers for pipes, so that only 64K
(or the amount of space specified by the -b option) is used
for the pipe. Warning: use of -B can result in erroneous
display, since only the most recently viewed part of the
file is kept in memory; any earlier data is lost.
I don't use the -B option, so I should be in the default case, where
"buffers are allocated automatically as needed".
This is particularly annoying with commands that need a lot of time
to complete.
-- System Information:
Debian Release: testing/unstable
APT prefers testing
APT policy: (900, 'testing'), (900, 'stable'), (200, 'unstable')
Architecture: powerpc (ppc)
Shell: /bin/sh linked to /bin/bash
Kernel: Linux 2.6.12-20050829
Locale: LANG=POSIX, LC_CTYPE=en_US.ISO8859-1 (charmap=ISO-8859-1)
Versions of packages less depends on:
ii debianutils 2.15.2 Miscellaneous utilities specific t
ii libc6 2.3.5-8 GNU C Library: Shared libraries an
ii libncurses5 5.5-1 Shared libraries for terminal hand
less recommends no packages.
-- no debconf information
--
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
