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UGU: Unix Guru Universe - Unix Tip #4323- January 11, 2025
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Unix Tip #4323- January 11, 2025
I SED BLANK
Using sed, you can remove blank lines, and
lines that contain only whitespace, from a
file using the following:
sed -e '/^[ ]*$/d' InputFile >OutputFile
Within the single quotes ('), the forward
slashes (/) delimit the regular expression
that will be interpreted by sed. The "d"
before the closing single quote, tells sed
to delete any lines that match the regular
expression.
Within the regular expression, the caret
(^) matches the beginning of a line.
The []* matches zero to many occurrences of
the character list between the open bracket
([) and the close bracket (]) (in the above
regular expression, you must insert a space
and a tab between the brackets). The dollar
sign ($) matches the end of a line.
These three constructs together match any
blank line or any line that contains only
spaces and tabs (in any combination).
Since the standard operation of sed is to
echo lines to stdout, all lines except blank
lines (or lines that only contain whitespace)
will be sent to OutputFile.
This tip generously supported by: tim.couger@wcom.com
NOTE: All tips provided are USE AT YOUR OWN RISK. Tips are submitted
by various unix admins around the globe. UGU suggest you read and
test each tip in a non-volitile environment before placing into
production.
LAST 5 TIPS
4322
- FILES OPENED BY A PROCESS
4321
- BACKUP THE REMOTE ESSENTIALS
4320
- STRING REMOVAL
4319
- KILLING MORE USERS
4318
- BASH HOTKEYS
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