I used fish for a couple of years and really liked it. But I recently learned that I can configure ZSH to have all of the same auto-complete and plugins that I loved from fish. Now I have all of the creature comforts I like, with POSIX compliance
I found that while fish has better syntax than bash for most things, the hassles with incompatibility or unexpected behavior brought me much more trouble than BASH's syntax ever has
I found that while fish has better syntax than bash for most things, the hassles with incompatibility or unexpected behavior brought me much more trouble than BASH's syntax ever has