What does the command cp $1/. $2 do? I know cp is used for copying from source(stored in variable $1) to destination(stored in variable $2). I am just confused with the /. used along with the variable. Can someone please help me understand this?
The command:
$ cp -R $1/. $2
copies contents of directory pointed by $1 to the directory $2.
Without -R switch this command would fail both when $1 is a file or directory.
In general, . points to the current directory. You can see that by comparing inode's shown by ls:
$ mkdir test
$ ls -ali
9525121 drwxr-xr-x 3 IU wheel 102 23 mar 12:31 .
771046 drwxrwxrwt 21 root wheel 714 23 mar 12:30 ..
9525312 drwxr-xr-x 2 IU wheel 68 23 mar 12:31 test
$ cd test
$ ls -ali
9525312 drwxr-xr-x 2 IU wheel 68 23 mar 12:31 .
9525121 drwxr-xr-x 3 IU wheel 102 23 mar 12:31 ..
Note that inode 9525312 points to test when viewed from the parent directory, and points to . when viewed from inside the test directory.
Related
I have directory of files called:
foo--ext1
foo--ext2
foo--ext3
...
I would like to rename them to:
foo-bar-ext1
foo-bar-ext2
foo-bar-ext3
....
How can I do this renaming in bash?
I have attempted to understand mywiki.wooledge.org/BashFAQ/030 but I can't work what should go in place of ${f%.foo}.bar"; in the first example.
So I have started with:
for f in foo--*; do echo mv -- "$f"
but what do I put next?
There are several ways to approach this.
I recommend bookmarking this page and referencing it often.
I would use this:
$: for f in foo--*; do mv "$f" "${f//foo--/foo-bar-}"; done
This uses string substitution in the current filename to construct the new name, replacing foo-- with foo-bar-.
Note the // in the replacement. This will replace every occurrence of foo-- with foo-bar- in each filename.
$: ls -l foo-*
-rw-r--r-- 1 paul 1049089 0 Jul 26 14:32 foo-bar-ext1
-rw-r--r-- 1 paul 1049089 0 Jul 26 14:32 foo-bar-ext2
-rw-r--r-- 1 paul 1049089 0 Jul 26 14:32 foo-bar-ext3
-rw-r--r-- 1 paul 1049089 0 Jul 26 14:33 foo-bar-foo-bar-etx4
Remove one of the leading slashes to make it only handle the first occurrence -
$: for f in foo--*; do mv "$f" "${f/foo--/foo-bar-}"; done
$: ls -l foo-*
-rw-r--r-- 1 paul 1049089 0 Jul 26 14:34 foo-bar-ext1
-rw-r--r-- 1 paul 1049089 0 Jul 26 14:34 foo-bar-ext2
-rw-r--r-- 1 paul 1049089 0 Jul 26 14:34 foo-bar-ext3
-rw-r--r-- 1 paul 1049089 0 Jul 26 14:34 foo-bar-foo--ext4
Another simple method avoiding the loop is to use rename (from the util-linux package). There all that is needed is:
rename "foo-" "foo-bar" foo--*
You can check what will be done before actually doing the rename with the -n (no-act) and -v (verbose) options. For your example files, that would be:
$ rename -nv "foo-" "foo-bar" foo--*
`foo--ext1' -> `foo-bar-ext1'
`foo--ext2' -> `foo-bar-ext2'
`foo--ext3' -> `foo-bar-ext3'
There are two versions of rename that you will find provided in Linux distributions, the rename above from the util-linux package and perl-rename, which some Linux distros use instead which will also install as rename. Both are capable of handling the rename, but the options will be different. Check which you have with rename --version before use.
I have a tricky configuration about ls command. Indeed, I am using grc colorifying the results od different terminal commands using iTerm2 into MacOS Catalina. My issue is about ls, I have for the moment into my .zshrc :
function ls { grc -es --colour=auto ls --color -Gh -C -rt "$#" ;}
and when I type |~/Test_data| ls, I get for example :
But the issue occurs when I am using for example a loop command with ls :
|~/Test_data| for i in $(ls); do echo $i | xargs ls -lrt; done
Indeed, I get as results :
ls: cannot access ''$'\033''[0m'$'\033''[01;37m'$'\033''[m'$'\033''[00;37mdata_0.txt'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[00;37mdata_4.txt'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[00;36mdata_3.py'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[01;37mdata_2.dat'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[01;35mdata_1.png'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[00;37mdata_1.txt'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[00;36mdata_0.py'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[00;36mdata_4.py'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[01;37mdata_3.dat'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[01;35mdata_2.png'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[00;37mdata_2.txt'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[00;36mdata_1.py'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[01;37mdata_0.dat'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[01;37mdata_4.dat'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[01;35mdata_3.png'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[00;37mdata_3.txt'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[00;36mdata_2.py'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[01;37mdata_1.dat'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[01;35mdata_0.png'$'\033''[0m': No such file or directory
ls: cannot access ''$'\033''[01;37m'$'\033''[m'$'\033''[01;35mdata_4.png'$'\033''[0m': No such file or directory
The results of ls command in for i in $(ls) loop generates ansi codes that cannot be processed by pipe xargs ls -lrt.
A workaround is to write in this case :
|~/Test_data| for i in $(ls --color=never); do echo $i | xargs ls -lrt; done
and I get a "normal" list of files :
~/Test_data| for i in $(ls --color=never); do echo $i | xargs ls -lrt; done
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_0.txt
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_4.txt
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_3.py
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_2.dat
-rw-r--r-- 1 fab staff 0 Apr 28 10:34 data_1.png
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_1.txt
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_0.py
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_4.py
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_3.dat
-rw-r--r-- 1 fab staff 0 Apr 28 10:34 data_2.png
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_2.txt
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_1.py
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_0.dat
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_4.dat
-rw-r--r-- 1 fab staff 0 Apr 28 10:34 data_3.png
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_3.txt
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_2.py
-rw-r--r-- 1 fab staff 0 Apr 28 10:32 data_1.dat
-rw-r--r-- 1 fab staff 0 Apr 28 10:34 data_0.png
-rw-r--r-- 1 fab staff 0 Apr 28 10:34 data_4.png
But I am bored to specify the option --color=never for ls at each time in my Shell scripts.
So I have found another alternative to remove these ansi codes by putting into my ~/.zshrc :
function ls { grc -es --colour=auto ls --color -Gh -C -rt "$#" | gsed -r 's/'$(echo -e "\033")'\[[0-9]{1,2}(;([0-9]{1,2})?)?[mK]//g' ;}
This way, I have not to use --color=never but Now, I loose colorified results of a simple |~| ls commmand.
So, to summarize, I would like to keep, when I type the simple command ls, the colorifying of my first function (function ls { grc -es --colour=auto ls --color -Gh -C -rt "$#" ;}) while being able to use ls into for i in $(ls ...); do ...; done loop of Shell scripts without specifying at each time the option --color=never.
I don't know if it possible to switch between the 2 specifications. For example, maybe I could detect automatically if ls command is included in a for loop of shell script?
Have you tried ?
function ls { local color; [ -t 1 ] && color="--color"; grc -es --colour=auto ls $color -Gh -C -rt "$#" ;}
I was toying with the idea of creating an alias that would allow me to list the contents of a target subdirectory, without changing to that directory.
I have successfully been able to create both an alias and a script to change directory and display contents. I call the script leap and it is simply:
#!/bin/bash
PATH=/bin:/usr/bin:.
# script to change to a directory, then display current contents
cd $1 && ls -l -a
The alias I use to trigger leap is defined: alias lp='. ~/scripts/leap'
My hope was I could simply create an alias named pk (pk is for peek) and concatenate my leap script and a standard bash command using &&. I could not be more wrong.
Current Directory
For reference, here is the contents of my current home directory (my user id has been replaced with $$$$):
drwxr-xr-x 3 $$$$$$ 46374 23 Aug 30 11:40 Fall_2019
drwxr-xr-x 5 $$$$$$ 46374 66 Aug 28 09:01 PAST_COURSES
drwxr-xr-x 3 $$$$$$ 46374 22 Aug 30 12:03 repos
drwxr-xr-x 3 $$$$$$ students 117 Aug 31 09:06 scripts
The Attempt(s)
Using alias pk='lp $1 && cd ..'
Entering [$$$$#host ~]$ pk PAST_COURSES results in:
-rw------- 1 $$$$$$ students 1766 Feb 28 2018 ~
drwx------ 10 $$$$$$ students 4096 Aug 31 09:06 .
drwx--x--x 1232 root root 28672 Aug 30 16:03 ..
-rw------- 1 $$$$$$ students 11368 Aug 30 12:20 .bash_history
-rw------- 1 $$$$$$ students 18 Aug 21 2017 .bash_logout
-rw------- 1 $$$$$$ students 180 Mar 8 2018 .bash_profile
-rw------- 1 $$$$$$ students 526 Aug 30 11:19 .bashrc
-rw------- 1 $$$$$$ students 266 Aug 21 2017 .cshrc
drwxr-xr-x 3 $$$$$$ 46374 23 Aug 30 11:40 Fall_2019
drwxr-xr-x 8 $$$$$$ students 155 Aug 30 12:14 .git
-rw-r--r-- 1 $$$$$$ students 87 Apr 11 2018 .gitconfig
-rw-r--r-- 1 $$$$$$ students 12288 Jan 29 2018 .hello.swp
-rw------- 1 $$$$$$ students 172 Aug 21 2017 .kshrc
-rw------- 1 $$$$$$ students 189 Mar 13 2018 .lesshst
-rw-r--r-- 1 $$$$$$ students 20480 Jan 29 2018 .ls.swn
drwxr-xr-x 5 $$$$$$ 46374 66 Aug 28 09:01 PAST_COURSES
drwxr----- 3 $$$$$$ 46374 18 Aug 30 12:16 .pki
drwxr-xr-x 3 $$$$$$ 46374 22 Aug 30 12:03 repos
drwxr-xr-x 3 $$$$$$ students 117 Aug 31 09:06 scripts
drwx------ 3 $$$$$$ students 103 Aug 30 11:12 .ssh
-rw------- 1 $$$$$$ students 12288 Sep 6 2017 .swp
drwxr-xr-x 2 $$$$$$ 46374 23 Aug 31 09:06 .vim
-rw-r--r-- 1 $$$$$$ students 8129 Aug 31 09:06 .viminfo
-rw-r--r-- 1 $$$$$$ students 142 Feb 14 2018 .vimrc
[$$$$#host home]$
As you can see, this displays the current directory ( ~ ) rather than switching to PAST_COURSES and displaying it. Additionally, the alias jumps up one directory above the current directory ( ~ ) rather than returning to it from PAST_COURSES.
Incidentally, I also get this exact result when I try using the following aliases:
pk='. ~/scripts/leap $1 && cd ..'
(using the script for leap rather than the alias)
pk='cd $1 && ls -l -a && cd ..'
(using the exact code inside leap )
Findings
In my tinkering I have noticed a few things:
First, if I simply type $$$$#host ~]$ ~/scripts/leap *[dir-name]* I actually get EXACTLY what I want - a look into a directory without changing to it. All by omitting the leading ., which boggles me.
Second, I can fix the current pk alias by changing the trailing cd .. to cd $(pwd), though it will not display the target directory instead of the current one.
At this point, I'd like a little help - not just in a script or alias that will do the job. An explanation that explains this behavior that I'm seeing would be marvelous.
Don't use . (the source builtin)
alias pk='. ~/scripts/leap $1 && cd ..' (using the script for leap rather than the alias)
is not equivalent to
alias pk='cd $1 && ls -l -a && cd ..'
In the first one, the . builtin (also known as source) is used, while in the second it is not. . doesn't just execute a command, it executes it in the current shell context. From the documentation:
. (a period)
. filename [arguments]
Read and execute commands from the filename argument in the current shell context.
That means anything the script does effects your current shell context. If the script changes directories, so does your current context.
If, on the other hand, the first version omitted the . like this:
alias pk='~/scripts/leap $1 && cd ..'
then the contents of the leap script would run in it's own bash context, but your current context would move up one directory (since the cd .. isn't inside the leap script).
Additional Recommendation on Functions vs Aliases
You could implement pk using a function like this:
pk() {
pushd $1
if [[ $? == 0 ]]; then
# Successfully changed directories.
# Run command
$2
# Return from the pre-pushd directory.
popd
fi
}
From the Bash Manual | 6.6 Aliases:
For almost every purpose, shell functions are preferred over aliases.
Example Alias
alias foo="echo bar"
Equivalent Function
foo() {
echo bar
}
I have this small script:
#!/bin/bash
for file in "$(ls | grep -v $0)";do
cat $file > "${file}-test"
done
On this directory:
total 40
-rwxr-xr-x 1 root root 783 Dec 11 09:19 appendToLog.sh
-rwxr-xr-x 1 root root 3995 Dec 11 13:22 con2dd.py
-rwxr-xr-x 1 root root 362 Dec 11 13:26 dd.py
-rw-r--r-- 1 root root 566 Dec 11 13:26 dd.pyc
-rw-r--r-- 1 root root 18558 Dec 25 11:24 moshe.log
-rw------- 1 root root 0 Dec 11 09:20 nohup.out
-rwxr-xr-x 1 root root 88 Dec 25 11:28 task.sh
-rwxr-xr-x 1 root root 560 Dec 11 10:33 test.py
Nevermind that I can achieve that with cp, I want to understand why this exactly is producing this file:
-rw-r--r-- 1 root root 24912 Dec 25 11:28 appendToLog.sh?con2dd.py?dd.py?dd.pyc?moshe.log?nohup.out?task.sh?test.py-test
And nothing else.
The problem is parsing output of ls is just wrong (see Why you shouldn't parse the output of ls(1), filenames in unix can have almost any special characters including whitespace, newlines, commas, pipe symbols. Its because you've quoted the output of ls in one construct, you have a single list of all the files concatenated as one string in the value of "${file}-test" which is quite not what you wanted to do.
Also notice how ls sometimes garbles your filename data (in our case, it turned the \n character in between the words into a ? question mark (could indicate a character that cannot be displayed).
Just use the glob expansion in bash to list the files and do actions on them.
for f in *; do
[[ -e $f ]] || continue
...
done
That said, You could probably have some non-printable characters on end of lines (eg. CRLF imported rom Windows)
Run cat -A scriptname it'll show you all characters in your script. Then, you can convert to unix-like format running dos2unix scriptname.
I was looking for a way to cp a file and mod its perms to 400 at the same time... after some testing in the public_html folder...
public_html >> ls -lah
-rw-r--r-- 1 user user 0 Feb 27 14:21 a.txt
public_html >> cp a.txt{,.bak}
-rw-r--r-- 1 user user 0 Feb 27 14:21 a.txt
-rw-r--r-- 1 root root 0 Feb 27 14:23 a.txt.bak
perms are still the same (644) and although the file is owned by root, it is still readable via public_html
public_html >> cp a.txt{,.bak} && chmod 400 a.txt.bak
-rw-r--r-- 1 user user 653 Feb 27 14:26 a.txt
-r-------- 1 root root 653 Feb 27 14:30 a.txt.bak
this works but looking for something for a set newbs to use
awk/sed command possibly?
dont think I'm missing a cp flag that could modify the perms, wasn't seeing anything and don't think there are but wanted to pick the collective brain
thanks...
install(1) can both copy files and create directories, and set their permissions at the same time.
install -m 0400 foo bar/