I wrote this one liner in bash:
while read line; printf $line' '; do : ; done < someFile
and it seemed to go over the lines of the files fine, but then it went into an infinite loop typing spaces. I realized my mistake was putting the printf before the do instead of after, but I still don't understand what's going on in here. Why do I get an infinite loop?
You've misplaced do. You want:
while read line; do printf "%s" "$line "; done < someFile
The way you've written it is valid, but the semantics are not what you expect.
while read line; printf $line' '; do : ; done < someFile
is reading the line and then printing it. The value returned by printf is evaluated to determine if the loop body is entered. Since printf succeeds, it enters the loop.
The general syntax is while {list of commands}; do {list of commands}; done The first list of commands is executed, and the result of the final command is evaluated to determine if the loop body is entered.
But it seems what you really want is:
tr \\n ' ' < someFile
do, it's written in the question, but the explanation is helpful. Also the : is just a place holder here, I did other stuff with line in therethe correct syntax is
while read line; do printf $line' '; done < someFile
try it ;)
if write in multi-line script if better to understand
#!/bin/bash
while read line
do
printf $line' '
done < SomeFile
code while IFS= read -r line; do COMMAND_on $line; done code
printf $line' 'which will most likely fail if the value oflinestarts with a dash (this is BTW a way to unintentionally break your infinite loop). Doprintf '%s ' "$line"instead.