I have written a simple shell script to do some automation work. Basically the script searches for all the files in the current path and if the file is a specified one, it does some action.
Below are the relevant lines ---
#!/bin/bash
for i in `ls *`
do
if [$i =="ls.sh"]
then .... //do something
fi
done
However, the string comparision in line 3 is not working and I am getting this when I run the script --
./ls.sh: line 3: [scripth.sh: command not found
./ls.sh: line 3: [scripth.sh~: command not found
./ls.sh: line 3: [test.sh: command not found
What is the correction to be done ?
first of all, don't use ls like that. It will go bonkers if your files have spaces!.
Use shell expansion. Then, you can use case/esac to make string comparison. (or if/else)
for file in *
do
case "$file" in
"ls.sh" ) echo "do something"
;;
esac
done
There are several problems.
In line 1, you are not doing what you think you are. You should put a backquote around ls *:
for i in `ls *`
That will go through all files that list in the current directory. Your line will not run any command, but instead it will use * to get all files and your list will include a word "ls" at the front.
try this from a command line:
echo ls *
echo `ls *`
You might just want to do:
for i in *
Second problem. Put spaces inside your square brackets:
[ $i == "ls.sh" ]
The spaces are necessary.
Third problem. Use one = for string comparison
[ $i = "ls.sh" ]
Use: if [ "$i" = "ls.sh" ] - notice the spaces.
If you only want to check the existing of a file, you could do it directly in shell.
if [ -e ls.sh ]
then
# ... do something
fi
You have not included a space after ==, so your code should actually be:
#!/bin/bash
for i in `ls *`
do
if [ $i == "ls.sh" ]
then
//do something
fi
done
Related
I have a folder with a ton of old photos with many duplicates. Sorting it by hand would take ages, so I wanted to use the opportunity to use bash.
Right now I have the code:
#!/bin/bash
directory="~/Desktop/Test/*"
for file in ${directory};
do
for filex in ${directory}:
do
if [ $( diff {$file} {$filex} ) == 0 ]
then
mv ${filex} ~/Desktop
break
fi
done
done
And getting the exit code:
diff: {~/Desktop/Test/*}: No such file or directory
diff: {~/Desktop/Test/*:}: No such file or directory
File_compare: line 8: [: ==: unary operator expected
I've tried modifying working code I've found online, but it always seems to spit out some error like this. I'm guessing it's a problem with the nested for loop?
Also, why does it seem there are different ways to call variables? I've seen examples that use ${file}, "$file", and "${file}".
You have the {} in the wrong places:
if [ $( diff {$file} {$filex} ) == 0 ]
They should be at:
if [ $( diff ${file} ${filex} ) == 0 ]
(though the braces are optional now), but you should allow for spaces in the file names:
if [ $( diff "${file}" "${filex}" ) == 0 ]
Now it simply doesn't work properly because when diff finds no differences, it generates no output (and you get errors because the == operator doesn't expect nothing on its left-side). You could sort of fix it by double quoting the value from $(…) (if [ "$( diff … )" == "" ]), but you should simply and directly test the exit status of diff:
if diff "${file}" "${filex}"
then : no difference
else : there is a difference
fi
and maybe for comparing images you should be using cmp (in silent mode) rather than diff:
if cmp -s "$file" "$filex"
then : no difference
else : there is a difference
fi
In addition to the problems Jonathan Leffler pointed out:
directory="~/Desktop/Test/*"
for file in ${directory};
~ and * won't get expanded inside double-quotes; the * will get expanded when you use the variable without quotes, but since the ~ won't, it's looking for files under an directory actually named "~" (not your home directory), it won't find any matches. Also, as Jonathan pointed out, using variables (like ${directory}) without double-quotes will run you into trouble with filenames that contain spaces or some other metacharacters. The better way to do this is to not put the wildcard in the variable, use it when you reference the variable, with the variable in double-quotes and the * outside them:
directory=~/"Desktop/Test"
for file in "${directory}"/*;
Oh, and another note: when using mv in a script it's a good idea to use mv -i to avoid accidentally overwriting another file with the same name.
And: use shellcheck.net to sanity-check your code and point out common mistakes.
If you are simply interested in knowing if two files differ, cmp is the best option. Its advantages are:
It works for text as well as binary files, unlike diff which is for text files only
It stops after finding the first difference, and hence it is very efficient
So, your code could be written as:
if ! cmp -s "$file" "$filex"; then
# files differ...
mv "$filex" ~/Desktop
# any other logic here
fi
Hope this helps. I didn't understand what you are trying to do with your loops and hence didn't write the full code.
You can use diff "$file" "$filex" &>/dev/null and get the last command result with $? :
#!/bin/bash
SEARCH_DIR="."
DEST_DIR="./result"
mkdir -p "$DEST_DIR"
directory="."
ls $directory | while read file;
do
ls $directory | while read filex;
do
if [ ! -d "$filex" ] && [ ! -d "$file" ] && [ "$filex" != "$file" ];
then
diff "$file" "$filex" &>/dev/null
if [ "$?" == 0 ];
then
echo "$filex is a duplicate. Copying to $DEST_DIR"
mv "$filex" "$DEST_DIR"
fi
fi
done
done
Note that you can also use fslint or fdupes utilities to find duplicates
Hi… Need a little help here…
I tried to emulate the DOS' dir command in Linux using bash script. Basically it's just a wrapped ls command with some parameters plus summary info. Here's the script:
#!/bin/bash
# default to current folder
if [ -z "$1" ]; then var=.;
else var="$1"; fi
# check file existence
if [ -a "$var" ]; then
# list contents with color, folder first
CMD="ls -lgG $var --color --group-directories-first"; $CMD;
# sum all files size
size=$(ls -lgGp "$var" | grep -v / | awk '{ sum += $3 }; END { print sum }')
if [ "$size" == "" ]; then size="0"; fi
# create summary
if [ -d "$var" ]; then
folder=$(find $var/* -maxdepth 0 -type d | wc -l)
file=$(find $var/* -maxdepth 0 -type f | wc -l)
echo "Found: $folder folders "
echo " $file files $size bytes"
fi
# error message
else
echo "dir: Error \"$var\": No such file or directory"
fi
The problem is when the argument contains an asterisk (*), the ls within the script acts differently compare to the direct ls command given at the prompt. Instead of return the whole files list, the script only returns the first file. See the video below to see the comparation in action. I don't know why it behaves like that.
Anyone knows how to fix it? Thank you.
Video: problem in action
UPDATE:
The problem has been solved. Thank you all for the answers. Now my script works as expected. See the video here: http://i.giphy.com/3o8dp1YLz4fIyCbOAU.gif
The asterisk * is expanded by the shell when it parses the command line. In other words, your script doesn't get a parameter containing an asterisk, it gets a list of files as arguments. Your script only works with $1, the first argument. It should work with "$#" instead.
This is because when you retrieve $1 you assume the shell does NOT expand *.
In fact, when * (or other glob) matches, it is expanded, and broken into segments by $IFS, and then passed as $1, $2, etc.
You're lucky if you simply retrieved the first file. When your first file's path contains spaces, you'll get an error because you only get the first segment before the space.
Seriously, read this and especially this. Really.
And please don't do things like
CMD=whatever you get from user input; $CMD;
You are begging for trouble. Don't execute arbitrary string from the user.
Both above answers already answered your question. So, i'm going a bit more verbose.
In your terminal is running the bash interpreter (probably). This is the program which parses your input line(s) and doing "things" based on your input.
When you enter some line the bash start doing the following workflow:
parsing and lexical analysis
expansion
brace expansion
tidle expansion
variable expansion
artithmetic and other substitutions
command substitution
word splitting
filename generation (globbing)
removing quotes
Only after all above the bash
will execute some external commands, like ls or dir.sh... etc.,
or will do so some "internal" actions for the known keywords and builtins like echo, for, if etc...
As you can see, the second last is the filename generation (globbing). So, in your case - if the test* matches some files, your bash expands the willcard characters (aka does the globbing).
So,
when you enter dir.sh test*,
and the test* matches some files
the bash does the expansion first
and after will execute the command dir.sh with already expanded filenames
e.g. the script get executed (in your case) as: dir.sh test.pas test.swift
BTW, it acts exactly with the same way for your ls example:
the bash expands the ls test* to ls test.pas test.swift
then executes the ls with the above two arguments
and the ls will print the result for the got two arguments.
with other words, the ls don't even see the test* argument - if it is possible - the bash expands the wilcard characters. (* and ?).
Now back to your script: add after the shebang the following line:
echo "the $0 got this arguments: $#"
and you will immediatelly see, the real argumemts how your script got executed.
also, in such cases is a good practice trying to execute the script in debug-mode, e.g.
bash -x dir.sh test*
and you will see, what the script does exactly.
Also, you can do the same for your current interpreter, e.g. just enter into the terminal
set -x
and try run the dir.sh test* = and you will see, how the bash will execute the dir.sh command. (to stop the debug mode, just enter set +x)
Everbody is giving you valuable advice which you should definitely should follow!
But here is the real answer to your question.
To pass unexpanded arguments to any executable you need to single quote them:
./your_script '*'
The best solution I have is to use the eval command, in this way:
#!/bin/bash
cmd="some command \"with_quetes_and_asterisk_in_it*\""
echo "$cmd"
eval $cmd
The eval command takes its arguments and evaluates them into the command as the shell does.
This solves my problem when I need to call a command with asterisk '*' in it from a script.
I have this assignment to solve:
"Write a shell script that continuously reads words from the keyboard and
deletes them from all the files given in the command line."
I've tried to solve it, here's my attempt:
#!/bin/bash
echo "Enter words"
while (true)
do
read wrd
if [ "$wrd" != "exit" ]
then
for i in $#
do
sed -i -e 's/$wrd//g' $i
done
else
break
fi
done
This is the error that I receive after introducing the command: ./h84a.sh fisier1.txt
Enter words
suc
sed: can't read 1: No such file or directory
Sorry if I'm not very specific, it's my first time posting in here. I'm working in a terminal on Linux Mint which is installed on another partition of my PC. Please help me with my problem. Thanks!
I think you can simplify your script quite a lot:
#!/bin/bash
echo "Enter words"
while read -r wrd
do
[ "$wrd" = exit ] && break
sed -i "s/$wrd//g" "$#"
done
Some key changes:
The double quotes around the sed command are essential, as shell variables are not expanded within single quotes
Instead of using a loop, it is possible to pass all of the file names to sed at once, using "$#"
read -r is almost always what you want to use
I would suggest that you take care with in-place editing using the -i switch. In some versions of sed, you can specify the suffix of a backup file like -i.bak, so the original file is not lost.
In case you're not familiar with the syntax [ "$wrd" = exit ] && break, it is functionally equivalent to:
if [ "$wrd" = exit ]
then break
fi
$# expands to the number of arguments (so 1 in this case)
You probably meant to use $* or "$#"
Given file socat.conf
AUTOSTART=default
SOCAT_default="TCP4-LISTEN:3724,nodelay,fork,reuseaddr,su=nobody TCP4:your.wow.server.ip.address:3724,nodelay"
The relevant part of the bash script that reads this file:
[ ! -f /etc/default/socat.conf ] || . /etc/default/socat.conf
start () {
echo "Starting $DESC:"
maxfds
umask 027
cd /tmp
if test "x$AUTOSTART" = "xnone" -o -z "x$AUTOSTART" ; then
echo "Autostart disabled."
exit 0
fi
for NAME in $AUTOSTART ; do
ARGS=`eval echo \\\$SOCAT_$NAME`
echo $ARGS
start_socat
echo " $NAME $ARGS"
done
return $?
}
For the full file see here: https://blog.bentrax.de/2009/08/26/socat-start-automatisieren-und-iptables-regeln-laden/
My question is, how can I add another command to socat.conf? I tried with
AUTOSTART=default,another
SOCAT_default="TCP4-LISTEN:3724,nodelay,fork,reuseaddr,su=nobody TCP4:your.wow.server.ip.address:3724,nodelay"
SOCAT_another="..."
However this did not work. I am not very familiar with bash scripts to understand the for NAME in $AUTOSTART loop. I think the answer lays there. Any ideas?
The for NAME in $AUTOSTART works by splitting $AUTOSTART into words using the environmental variable $IFS as delimiters (default is space, tab and newline). Each word in turn is then stored in $NAME and processed within the loop until no words remain.
The solution to your problem, then, is to separate your words using spaces (or tabs, or newlines..):
AUTOSTART="default another"
The double quotes are necessary, otherwise it will be read as two separate commands, AUTOSTART=default and another (again because of word-splitting using IFS).
Let's say I have the following files in my current directory:
1.jpg
1original.jpg
2.jpg
2original.jpg
3.jpg
4.jpg
Is there a terminal/bash/linux command that can do something like
if the file [an integer]original.jpg exists,
then move [an integer].jpg and [an integer]original.jpg to another directory.
Executing such a command will cause 1.jpg, 1original.jpg, 2.jpg and 2original.jpg to be in their own directory.
NOTE
This doesn't have to be one command. I can be a combination of simple commands. Maybe something like copy original files to a new directory. Then do some regular expression filter on files in the newdir to get a list of file names from old directory that still need to be copied over etc..
Turning on extended glob support will allow you to write a regular-expression-like pattern. This can handle files with multi-digit integers, such as '87.jpg' and '87original.jpg'. Bash parameter expansion can then be used to strip "original" from the name of a found file to allow you to move the two related files together.
shopt -s extglob
for f in +([[:digit:]])original.jpg; do
mv $f ${f/original/} otherDirectory
done
In an extended pattern, +( x ) matches one or more of the things inside the parentheses, analogous to the regular expression x+. Here, x is any digit. Therefore, we match all files in the current directory whose name consists of 1 or more digits followed by "original.jpg".
${f/original/} is an example of bash's pattern substitution. It removes the first occurrence of the string "original" from the value of f. So if f is the string "1original.jpg", then ${f/original/} is the string "1.jpg".
well, not directly, but it's an oneliner (edit: not anymore):
for i in [0-9].jpg; do
orig=${i%.*}original.jpg
[ -f $orig ] && mv $i $orig another_dir/
done
edit: probably I should point out my solution:
for i in [0-9].jpg: execute the loop body for each jpg file with one number as filename. store whole filename in $i
orig={i%.*}original.jpg: save in $orig the possible filename for the "original file"
[ -f $orig ]: check via test(1) (the [ ... ] stuff) if the original file for $i exists. if yes, move both files to another_dir. this is done via &&: the part after it will be only executed if the test was successful.
This should work for any strictly numeric prefix, i.e. 234.jpg
for f in *original.jpg; do
pre=${f%original.jpg}
if [[ -e "$pre.jpg" && "$pre" -eq "$pre" ]] 2>/dev/null; then
mv "$f" "$pre.jpg" targetDir
fi
done
"$pre" -eq "$pre" gives an error if not integer
EDIT:
this fails if there exist original.jpg and .jpg both.
$pre is then nullstring and "$pre" -eq "$pre" is true.
The following would work and is easy to understand (replace out with the output directory, and {1..9} with the actual range of your numbers.
for x in {1..9}
do
if [ -e ${x}original.jpg ]
then
mv $x.jpg out
mv ${x}original.jpg out
fi
done
You can obviously also enter it as a single line.
You can use Regex statements to find "matches" in the files names that you are looking through. Then perform your actions on the "matches" you find.
integer=0; while [ $integer -le 9 ] ; do if [ -e ${integer}original.jpg ] ; then mv -vi ${integer}.jpg ${integer}original.jpg lol/ ; fi ; integer=$[ $integer + 1 ] ; done
Note that here, "lol" is the destination directory. You can change it to anything you like. Also, you can change the 9 in while [ $integer -le 9 ] to check integers larger than 9. Right now it starts at 0* and stops after checking 9*.
Edit: If you want to, you can replace the semicolons in my code with carriage returns and it may be easier to read. Also, you can paste the whole block into the terminal this way, even if that might not immediately be obvious.