Line-buffering the output when forewarding to a file

[akash_rawal]

There's a line in pupdial:

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wvdial ${WVISP} ${WVPIN} ${WVAPN} ${WVWRLS} &> /tmp/pupdial.log &

/tmp/pupdial.log is updated after every line of output and can be viewed in wvdial connection log.

When I try to achieve a similar thing for the volume monitor, the output is full-buffered i.e. the output is not flushed after every line. Data gets written only when it has written about 1kb. None of the following work like I want.

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pup-volume-monitor &> "$LOG_FILE" #forewards stderr only

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pup-volume-monitor 2>&1 > "$LOG_FILE" #forewards stderr only

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pup-volume-monitor 2>&1 | cat > "$LOG_FILE" #full buffered output

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pup-volume-monitor 2>&1 | grep --line-buffered "" > "$LOG_FILE" #full buffered output

How can I achieve line buffering, please help!

[jemimah]

The only way I know of is to add explicit buffer flushes to the C code with

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fflush(stdout)

.

[Karl Godt]

Cannot find any pup-volume-monitor on the forum .

&>FILE should mean stdout and stderr to FILE . Probably the ' &' fork at the very end of the line is needed here.

Some programs still issue output to the console even with &>FILE.