Question

Suppose I have variable “x” in bash. How can I test if it’s some number?

I tried if x=5; then echo "it is 5"; fi but that doesn’t work,

then I tried if x==5; then echo "it is 5"; fi but that also doesn’t work,

then I tried if [x==5]; then echo "it is 5"; fi but that also doesn’t work,

then I tried if [[x==5]]; then echo "it is 5"; fi but that also doesn’t work,

then I tried if [[x=5]]; then echo "it is 5"; fi but that also doesn’t work,

then I tried if [x=5]; then echo "it is 5"; fi but that also doesn’t work,

then I tried if [x -eq 5]; then echo "it is 5"; fi but that also doesn’t work,

then I tried if [[x -eq 5]]; then echo "it is 5"; fi and it finally worked.

I am lost. Bash seems to be hell. Why so many ways didn’t work? And only the last one did?

Can’t bash adopt if x==5; then ...; fi syntax?

Thanks, Boda Cydo

Answer 1

Try:

if [ "$x" = 5 ]; then echo "it is 5"; fi

Note that [ is a command in itself; you may find that it’s symlinked to test on your system. So, man test tells you how to use it. In particular, it is important to put a space after it.