Re: Feature request: --progress option to wc(1) - [Solved] [Accepted]

[Joakim Lindblad]

Fair enough Pádraig.

Felt it was a bit overkill/overcomplex with pv, but it does solve the problem. 
With a bit of string processing (irritatingly pv does not combine -F format 
with -n plain integer output).


This is my solution (with sed to prepend '\r' and tr to eat '\n' and echo to 
add a '\n' at the very end) :

tar -tf big.tar | pv -i 0.1 -lbnX 2>&1 | stdbuf -o0 sed -e 's/^/\r/' | stdbuf 
-o0 tr -d '\n'; echo;



A small timing test on 1,000,000,000 lines shows that the overhead is 
negligible (and I learnt that 'seq' is significantly slower than 'yes | head')

$ time { yes | head -n 1000000000 >/dev/null ; }

real    0m1,976s
user    0m1,539s
sys     0m1,155s

$ time { yes | head -n 1000000000 | wc -l ; }
1000000000

real    0m2,545s
user    0m2,043s
sys     0m2,359s

$ time { yes | head -n 1000000000 | pv -i 0.1 -lbnX 2>&1 | stdbuf -o0 sed -e 
's/^/\r/' | stdbuf -o0 tr -d '\n'; echo; }
1000000000

real    0m2,649s
user    0m3,889s
sys     0m2,085s


Cheers!
/ Joakim




On 2024-11-15 17:57, Pádraig Brady wrote:
On 15/11/2024 15:40, Joakim Lindblad wrote:
I'm often using 'wc' for stuff that takes a long time, e.g. 'tar -tf big.tar | 
wc -l' to count the
files in an archive.
Here I am lacking some intermediate feedback from the process.

Does a "--progress" version of 'wc' exist? I am envisioning a continuous count 
with a simple
line-wise overwrite a'la '\r'.

I fail to find the option, and I don't find the feature request rejected
https://www.gnu.org/software/coreutils/rejected_requests.html#wc

I could potentially volunteer to implement it (but am happy not to).

Yes this does seem like useful functionality,
however it's already implemented in `pv --line-mode`,
so I don't see an advantage to implementing in wc.

For example:

while :; do seq 10; sleep 1; done | pv --line-mode > /dev/null

thanks,
Pádraig

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--
_______________________________________________________________
Joakim Lindblad, PhD, Docent          E-mail: 
joakim@cb.uu.se<mailto:joakim@cb.uu.se>
Prof. Computerized Image Processing   Phone: +46-733-168549
Dept. of IT, Uppsala University       http://cb.uu.se/~joakim
_______________________________________________________________










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