Bash变量在OSX终端中返回“未找到命令”

Question

I tried using some variables to rename a few files, but it failed miserably. I've tried different ways of getting it to work, but to no avail. As far as I understand the documentation, this is the correct way of doing things - however now I'm stumped...

Here's the code (as written in the file rename_prefix.sh ):

 #!/bin/sh
 NEWPREF="LALA"
 OLDPREF="LULU"
 for f in $OLDPREF*; do mv $f $(echo $f | sed 's/^$OLDPREF/$NEWPREF/g'); done

Here's the error message:

 usage: mv [-f | -i | -n] [-v] source target
   mv [-f | -i | -n] [-v] source ... directory

Initially I thought the problem lay in using variables with what I assume are the regular expressions, but as can be seen from the error messages, the problem lies where the variables are first declared.

What's going on here?

Answer 1

This can be done entirely in the shell, which also avoids the possible problem of escaping metacharacters for the sed substitution patterns. It is also blazingly fast because it saves two forks per file renamed.

NEWPREF="LALA"
OLDPREF="LULU"
for f in "$OLDPREF"*; do
   mv "$f" "$NEWPREF${f#$OLDPREF}"
done

If you want to learn more about removing suffixes and prefixes from shell variable values, read up the POSIX spec on parameter expansion (which all of zsh, ksh, mksh, and bash support).

PS: The only way you can get an error like rename_prefix.sh: line 2: NEWPREF: command not found is if you had whitespace after NEWPREF and before the = . It looks very much like your program as posted is not exactly the program you ran. Did you type it instead of cut'n'paste it?

Answer 2

Alright so assuming you don't require POSIX, and guessing about certain other details, here's the same thing with general corrections applied.

#!/bin/bash
newpref=LALA
oldpref=LULU

shopt -s nullglob

for f in "$oldperf"*; do
    mv -- "$f" "${f/#"$oldpref"/$newpref}"
done

or POSIX

#!/bin/sh
newpref=LALA
oldpref=LULU

for f in "$oldpref"*; do
    [ -e "$f" ] || break
    mv -- "$f" "${newpref}${f#"$oldpref"}"
done