On 16/06/09 22:06, david wrote:
Q1.why does sed lose the first line?
> cat blah | while read line ; do sed s/t/T/ ; done
Think about the return value of sed with no input. while swallows the first line, then cat prints the rest. You want this: cat blah | while read line ; do echo "$line" | sed s/t/T/ ; done which will have trouble with some characters in the input. I don't understand why you didn't choose a direct file redirection rather than a pipe: sed s/t/T/ < blah
Q2. what does the @ mean?
> date -d @1174306440
I can't find a reference to @ in the date man page.
That man page says: The full documentation for date is maintained as a Texinfo manual. Which indeed it is: 28.8 Seconds since the Epoch ============================ If you precede a number with `@', it represents an internal time stamp as a count of seconds. The number can contain an internal decimal point (either `.' or `,'); any excess precision not supported by the internal representation is truncated toward minus infinity. Such a number cannot be combined with any other date item, as it specifies a complete time stamp. Internally, computer times are represented as a count of seconds since an epoch--a well-defined point of time. On GNU and POSIX systems, the epoch is 1970-01-01 00:00:00 UTC, so `...@0' represents this time, `...@1' represents 1970-01-01 00:00:01 UTC, and so forth... -- Glen Turner -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
