4 ms·
One advantage of "parallel --dry-run" over "xargs echo" is that the former quotes its output: $ touch 'Ham Jam Spam' $ touch 'J.R. "Bob" Dobbs'
by jasomill 13y ago
One advantage of "parallel --dry-run" over "xargs echo" is that the former quotes its output:
$ touch 'Ham
Jam
Spam'
$ touch 'J.R. "Bob" Dobbs'
$ find . -type f -print0 | parallel -n1 -0 --dry-run echo
echo ./Ham'
'Jam'
'Spam
echo ./J.R.\ \"Bob\"\ Dobbs
$ find . -type f -print0 | xargs -n1 -0 echo echo
echo ./Ham
Jam
Spam
echo ./J.R. "Bob" Dobbs
For my own "dry runs", though, I've always preferred passing the command line to
#include <stdio.h>
int main(int argc, char* argv[]) {
char** argp;
int i;
printf("argc = %d\n", argc);
for (i = 0, argp = argv; *argp != 0; ++argp, ++i) {
printf("argv[%d] = %s\n", i, *argp);
}
return 0;
}
to remove all reasonable doubt.
- lotsofcows 13y agoQuoting is nice. That's better than bash -x debug mode too.
- peterwwillis 13y agoWhy does the parallel example look weird? It put the single quotes in all the wrong places, and completely around Jam. It should have printed echo './Ham Jam Spam' but your output looks different. As an example of how it should look, try this: $ find . -type f -print0 | xargs -n1 -0 perl -e'print "\"$_\" " for (@ARGV)' "./Ham Jam Spam"
- seryoiupfurds 13y agoIt looks like it's only single-quoting the characters that need it, in his example the newlines.
- davvolun 13y agoHaving never used parallel, I still believe parallel was correct. ./Ham' 'Jam' 'Spam would be identical to ./Ham\nJam\nSpam (if \n were the correct translation to the newline in this case) or './Ham Jam Spam' This would be identical to what you wrote, but only punts to quotes when it doesn't have a canonical method of representing the character otherwise. The fact that you don't need to explicitly concatenate two strings in the shell may be what's throwing you off? Interestingly enough, 'Ham\n\nJam\nSpam' becomes ./Ham' '' 'Jam' 'Spam So parallel is just literally outputting all newlines using quotes. I believe this would be identical, if you analyzed it and saw that two newlines are next to each other: ./Ham' 'Spam' 'Jam