I'm trying to get a simple while loop working in bash that uses two conditions, but after trying many different syntax from various forums, I can't stop throwing an error. Here is what I have:
while [ $stats -gt 300 ] -o [ $stats -eq 0 ]
I have also tried:
while [[ $stats -gt 300 ] || [ $stats -eq 0 ]]
... as well as several others constructs. I want this loop to continue while $stats is > 300 or if $stats = 0.
The correct options are (in increasing order of recommendation):
# Single POSIX test command with -o operator (not recommended anymore).
# Quotes strongly recommended to guard against empty or undefined variables.
while [ "$stats" -gt 300 -o "$stats" -eq 0 ]
# Two POSIX test commands joined in a list with ||.
# Quotes strongly recommended to guard against empty or undefined variables.
while [ "$stats" -gt 300 ] || [ "$stats" -eq 0 ]
# Two bash conditional expressions joined in a list with ||.
while [[ $stats -gt 300 ]] || [[ $stats -eq 0 ]]
# A single bash conditional expression with the || operator.
while [[ $stats -gt 300 || $stats -eq 0 ]]
# Two bash arithmetic expressions joined in a list with ||.
# $ optional, as a string can only be interpreted as a variable
while (( stats > 300 )) || (( stats == 0 ))
# And finally, a single bash arithmetic expression with the || operator.
# $ optional, as a string can only be interpreted as a variable
while (( stats > 300 || stats == 0 ))
Some notes:
Quoting the parameter expansions inside [[ ... ]] and ((...)) is optional; if the variable is not set, -gt and -eq will assume a value of 0.
Using $ is optional inside (( ... )), but using it can help avoid unintentional errors. If stats isn't set, then (( stats > 300 )) will assume stats == 0, but (( $stats > 300 )) will produce a syntax error.
until as well, yes?
while [ foo -o bar ] becomes until ! [ foo -o bar ], but while foo || bar becomes until ! foo && ! bar.
while [[ read -r line && $inputdata != "" ]]; do. How do I achieve that?
while read -r theline && [ "$theline" != "" ]
while [[ $counter -le 97 -a "$breakCond" -le "$Mu"]]Try:
while [ $stats -gt 300 -o $stats -eq 0 ]
[ is a call to test. It is not just for grouping, like parentheses in other languages. Check man [ or man test for more information.
The extra [ ] on the outside of your second syntax are unnecessary, and possibly confusing. You may use them, but if you must you need to have whitespace between them.
Alternatively:
while [ $stats -gt 300 ] || [ $stats -eq 0 ]
[[ is generally the preferred built-in to introduce a test expression. It has several advantages over the older single [ syntax.