I have a basic bash script that i want to use to create a list of directories inside a file. The issue is that when i type the following command on the terminal it works fine but when used inside a function it does not
function Create_file_dirs()
{
ls | grep / > dirs.txt
cat dirs.txt #used for debugging
}
This function is inside a script and i'm running it by calling the script. ./script.sh
`
The command
ls | grep / > dirs.txt
works great on the terminal window and produces a file listing directories line by line, but doesn't do anything when used inside a function and i can't figure out why. Thanks
ls without options does not produce slashes, so grep doesn't find anything. You can easily reproduce it on the command line by, say,
comand ls|grep /
My thanks to William Pursell for his answer and to everyone who contributed.
The answer came from a comment made by William Pursell.
The working function is:
create_file_dirs()
{
ls -F | grep / >./dirs.txt
cat dirs.txt
}
The issue was,that when i was running the ls command on the terminal i could see a slash / after a directories name and running the command on the terminal actually produced the desired result.
ls | grep / > ./dirs.txt
It seems though running ls through a script doesn't produce a slash / after a directories name that is why i had to add them -F option to resolve this issue.
The way i tested it out was with this simple function inside a script and run the script. The result didn't have slashes.
test_dirs(){
ls | cat
}
Related
I have a script located at /usr/local/bin/gq which is returned by the command whereis gq, well almost. What is actually returned is gq: /usr/local/bin/gq. But the following gives me just the filepath (with some white space)
whereis gq | cut -d ":" -f 2
What I’d like to do is be able to pipe that into cat, so I can see the contents. However the old pipe isn’t working. Any suggestions?
If you want to cat the contents of gq, then how about:
cat $(which gq)
The command which gq will result in /usr/local/bin/gq, and the cat command will act on that.
If I have a file named w5_align_example.cpp, how do I open that file in VS Code integrated terminal by only supplying the word align?
code w5_align_sample.cpp would open it but I sometimes only remember the keyword align unless I search in a separate command to see what the file begins with. I want to open in a single command instead.
I've tried:
$ ls | grep "align" | code which gives me Run with 'code -' to read output from another program (e.g. 'echo Hello World | code -'). error.
$ ls | grep "align" | code - opens up a new file called code-stdin-sfd.txt with the text w5_align_example.cpp inside.
What would be the simplest (i.e. shortest) command to do this?
ls | grep "align" | xargs -I{} code {}
or
code $(ls | grep "align")
You can just use *. It matches any string and can be used multiple times.
code *align*
In some shells, you can combine this with tab completion. Just type:
code *align*
And then press Tab. This will fill in the rest of the file name, but it will beep if there is more than one option.
New to UNIX, currently learning UNIX via secureshell in a class. We've been given a few basic assignments such as creating loops and finding files. Our last assignment asked us to
write code that will estimate the number of shell scripts in the current directory and then print out that total number as "Estimated number of shell script files in this directory:"
Unlike in our previous assignments we are now allowed to use conditional loops, we are encouraged to use grep and wc statements.
On a basic level I know I can enter
ls * .sh
to find all shell scripts in the current directory. Unfortunately, this doesn't estimate the total number or use grep. Hence my question, I imagine he wants us to go
grep -f .sh (or something)
but I'm not exactly sure if I am on the right path and would greatly appreciate any help.
Thank You
You can do it like:
echo "Estimated number of shell script files in this directory:" `ls *.sh | wc -l`
I'd do it this way:
find . -executable -execdir file {} + | egrep '\.sh: | Bourne| bash' | wc -l
Find all files in the current directory (.) which are executable.
For each file, run the file(1) command, which tries to guess what type of file it is (not perfect).
Grep for known patterns: filenames ending with .sh, or file types containing "Bourne" or "bash".
Count lines.
Huhu, there's a trap, .sh file are not always shell script as the extension is not mandatory.
What tells you this is a shell script will be the Shebang #!/bin/*sh ( I put a * as it could be bash, csh, tcsh, zsh, which are shells) at top of line, hence the hint to use grep, so the best answer would be:
grep '^#!/bin/.*sh' * | wc -l
This give output:
sensible-pager:#!/bin/sh
service:#!/bin/sh
shelltest:#!/bin/bash
smbtar:#!/bin/sh
grep works with regular expression by default, so the match #!/bin/.*sh will match files with a line starting (the ^) by #!/bin/ followed by 0 or unlimited characters .* followed by sh
You may test regex and get explanation of them on http://regex101.com
Piping the result to wc -l to get the number of files containing this.
To display the result, backticks or $() in an echo line is ok.
grep -l <string> *
will return a list of all files that contain in the current directory. Pipe that output into wc -l and you have your answer.
Easiest way:
ls | grep .sh > tmp
wc tmp
That will print the number of lines, bytes and charcters of 'tmp' file. But in 'tmp' there's a line for each *.sh file in your working directory. So the number of lines will give an estimated number of shell scripts you have.
wc tmp | awk '{print $1}' # Using awk to filter that output like...
wc -l tmp # Which it returns the number of lines follow by the name of file
But as many people say, the only certain way to know a file is a shell script is by taking a look at the first line an see if there is #!/bin/bash. If you wanna develop it that way, keep in mind:
cat possible_script.x | head -n1 # That will give you the first line.
I'm working on a project, and it's being run by an autoscript. The script has the following line:
./executable ./dev | grep -i "GET.*index.*200" > ./dev/logs/log1
I have my code writing to stdout, but it never gets written to log1. If I change it though and remove the grep command, it writes just fine. Any help would be appreciated, as I seemingly don't understand grep as well as I should.
You might try to redirect std output in your script "executable" using commands:
exec > ./dev/logs/log1
exec 2> ./dev/logs/errlog1
So, now not need to use ">" in the line
./executable ./dev | grep -i "GET.*index.*200"
Also I recommend you to use only absolute paths in scripts.
ps. [offtop] I can't write comments yet (not enough reputation).
I have a directory full of files with one extension (.txt in this case) that I want to automatically convert to another extension (.md).
Is there an easy terminal one-liner I can use to convert all of the files in this directory to a different file extension?
Or do I need to write a script with a regular expression?
You could use something like this:
for old in *.txt; do mv $old `basename $old .txt`.md; done
Make a copy first!
Alternatively, you could install the ren (rename) utility
brew install ren
ren '*.txt' '#1.md'
If you want to rename files with prefix or suffix in file names
ren 'prefix_*.txt' 'prefix_#1.md'
Terminal is not necessary for this... Just highlight all of the files you want to rename. Right click and select "Rename ## items" and just type ".txt" into to the "Find:" box and ".md" into the "Replace with:" box.
The preferred Unix way to do this (yes, OS X is based on Unix) is:
ls | sed 's/^\(.*\)\.txt$/mv "\1.txt" "\1.md"/' | sh
Why looping with for if ls by design loops through the whole list of filenames? You've got pipes, use them. You can create/modify not only output using commands, but also commands (right, that is commands created by a command, which is what Brian Kernighan, one of the inventors of Unix, liked most on Unix), so let's take a look what the ls and the sed produces by removing the pipe to sh:
$ ls | sed 's/^\(.*\)\.txt$/mv "\1.txt" "\1.md"/'
mv "firstfile.txt" "firstfile.md"
mv "second file.txt" "second file.md"
$
As you can see, it is not only an one-liner, but a complete script, which furthermore works by creating another script as output. So let's just feed the script produced by the one-liner script to sh, which is the script interpreter of OS X. Of course it works even for filenames with spaces in it.
BTW: Every time you type something in Terminal you create a script, even if it is only a single command with one word like ls or date etc. Everything running in a Unix shell is always a script/program, which is just some ASCII-based stream (in this case an instruction stream opposed to a data stream).
To see the actual commands being executed by sh, just add an -x option after sh, which turns on debugging output in the shell, so you will see every mv command being executed with the actual arguments passed by the sed editor script (yeah, another script inside the script :-) ).
However, if you like complexity, you can even use awk and if you like to install other programs to just do basic work, there is ren. I know even people who would prefer to write a 50-lines or so perl script for this simple every-day task.
Maybe it's easier in finder to rename files, but if connected remotely to a Mac (e.g. via ssh), using finder is not possible at all. That's why cmd line still is very useful.
Based on the selected and most accurate answer above, here's a bash function for reusability:
function change_all_extensions() {
for old in *."$1"; do mv $old `basename $old ."$1"`."$2"; done
}
Usage:
$ change_all_extensions txt md
(I couldn't figure out how to get clean code formatting in a comment on that answer.)
No need to write a script for it just hit this command
find ./ -name "*.txt" | xargs -I '{}' basename '{}' | sed 's/\.txt//' | xargs -I '{}' mv '{}.txt' '{}.md'
You do not need a terminal for this one; here is a sample demonstration in MacOS Big Sur.
Select all the files, right-click and select "rename..."
Add the existing file extension in "Find" and the extension you want to replace with "Replace with".
And done!
I had a similar problem where files were named .gifx.gif at the end and this worked in OS X to remove the last .gif:
for old in *.gifx.gif; do
mv $(echo "$old") $(echo "$old" | sed 's/x.gif//');
done
cd $YOUR_DIR
ls *.txt > abc
mkdir target // say i want to move it to another directory target in this case
while read line
do
file=$(echo $line |awk -F. '{ print $1 }')
cp $line target/$file.md // depends if u want to move(mv) or copy(cp)
done < abc
list=ls
for file in $list
do
newf=echo $file|cut -f1 -d'.'
echo "The newf is $newf"
mv $file $newf.jpg
done