On 11/12/15 14:46, Stephane Chazelas wrote: > 2015-12-10 10:40:30 -0700, Bob Proulx: > [...] >> In this instance the first thing I thought of when I read your dirname >> -f request was a loop. >> >> while read dir; do dirname $dir; done < list > > "read dir" expects the input in a very specific format and > depends on the current value of IFS (like a dir called "my\dir " > has to be input as "my\\dir\ " with the default value of IFS) > and can't accept dir names with newline characters. > > Invoking the split+glob operator on $dir doesn't make sense here > unless you mean the input to be treated as a $IFS delimited list > of patterns. > > If the intention was to treat the input as a list of file > paths, one per line (so can't do file paths with newline > characters), then that would rather be: > > while IFS= read -r dir; do dirname -- "$dir"; done < list > >> >> Pádraig suggested xargs which was even shorter. >> >> xargs dirname < filename > > That expects yet another input format. That time, it can cope > with any file path, since newline can be specified using quotes > like: > > "my dir > with newline" > > The output of dirname however won't be post-processable.
Both GNU basename and dirname since 8.16 (2012) got the -z option to make the _output_ post-processable, along with support for processing multiple inputs. xargs splits arguments on the _input_ appropriately. In general xargs is fine for this when the tool doesn't need to process all inputs at once (like sorting or generating a total for example). cheers, Pádraig.
