Shell script change directory with variable

问题:

I know this question has been asked numerous times, but I still could not find any good solution. Hence, asking it again if anyone can help !!

I am trying to change a my working directory inside a shell script with help of a variable. But I get " No such file or directory" everytime.

#!/bin/bash
echo ${RED_INSTANCE_NAME}   <-- This correctly displays the directory name
cd $RED_INSTANCE_NAME       <-- This line gives the error

Now, when I try to give the actually directory name instead of using the variable, shell changes the directory without issues

cd test  <-- No error

Does anyone knows what can be the issue here ? Please help !!

回答1:

You variable contains a carriage return. Try saying:

cd $(echo $RED_INSTANCE_NAME | tr -d '\r')

and it should work. In order to remove the CR from the variable you can say:

RED_INSTANCE_NAME=$(echo $RED_INSTANCE_NAME | tr -d '\r')

---

The following would illustrate the issue:

$ mkdir abc
$ foo=abc$'\r'
$ echo "${foo}"
abc
$ cd "${foo}"
: No such file or directory
$ echo $foo | od -x
0000000 6261 0d63 000a
0000005
$ echo $foo | tr -d '\r' | od -x
0000000 6261 0a63
0000004
$ echo $'\r' | od -x
0000000 0a0d
0000002

回答2:

One way to encounter your described problem is to have a tilde (~) in the variable name. Use the absolute path or $HOME variable instead. Note that using $HOME will require double quotations.

# doesn't work
$ vartilde='~/'
$ cd $vartilde
-bash: cd: ~: No such file or directory

# works
$ varfullpath='/Users/recurvirostridae'
$ cd $varfullpath

# works
$ varwithhome="$HOME"
$ cd $varwithhome

回答3:

Try

cd "$RED_INSTANCE_NAME"

Also, make sure the path makes sense to the current directory where cd command is executed.

回答4:

I don't know what is going wrong for you, but I can offer one piece of general advice:

cd "$RED_INSTANCE_NAME"       # Quote the string in case it has spaces.error

You should nearly always put the "$VARIABLE" in quotes. This will protect from surprises when the value of the variable contains funny stuff (like spaces).

回答5:

You can check for carriage returns, ANSI escapes and other special characters with

cat -v <<< "$RED_INSTANCE_NAME"

This will show all the characters that echo $RED_INSTANCE_NAME would just hide or ignore.

In particular, if your error message is : No such file or directory as opposed to bash: cd: yourdir: No such file or directory, it means you have a carriage return at the end of your variable, probably from reading it from a DOS formatted file.

回答6:

I ran into a different issue. My "cd $newDir" was failing because I added logging into my script. Apparently if you add a pipe to any cd command it does nothing or gets gobbled up.

Wasted 3 hours figuring that out.

newDir=$oldDir/more/dirs/

cd $newDir #works

cd $newDir | tee -a log #does nothing

cd $newdir | echo hi    #does nothing

So cd with any pipe does nothing. No idea why cd fails. The pipe means finish what command you doing then feed any output to next command. This is on RHEL 7.
I was trying to log all my commands and hit this nice error. Figured I'd post it in case anyone else hits it.