I am trying to pass a user-input variable (a file name) into a foreach loop in tcsh. The user entered variable is, for example, "files.list" (saved in the same folder as the Shell Script is saved, and is being run from).
Here is my code:
#! /usr/bin/tcsh -f
echo please enter files list
set x = $<
foreach i ('$x')
echo $i
end
What I want is for each of the words in "files.list" to be output to the screen. Files.list contains 5 lines, each with a file name.
myScript22.sh
Mad45.sh
Number32.sh
killBill.sh
gotMilk.sh
bugslife.sh
I get an error - "foreach: Words not parenthesized."
Could it be that 'cat $x' isn't calling the x variable correctly? If so, how do I get the file set up so it's contents can be looped thru?
Any help is appreciated!
If you really really really really have to use tcsh, then the following is the propper way to do it:
#!/usr/bin/tcsh -f
echo please enter files list
set x = $<
foreach line (" `cat $x` ")
echo "$line"
end
It is important to see that the cat command is between <double-quotes>. The difference is that otherwise, the foreach statement will read word-by-word, while the double-quoted version will read line-by-line. The logic of this is ... questionable. Also, I quoted the variable line in the echo statement, because it will actually complain when it hits an empty line.
In bash, you would just do the following nice thing:
#!/usr/bin/env bash
echo "Please enter files list"
file=""
while [[ ! -e $file ]]; do read -r file; done
while read -r line; do
echo "$line"
done < "$file"
Very important reads:
CSH PROGRAMMING CONSIDERED HARMFUL
Top Ten Reasons not to use the C shell
For reference purposes, I was missing the cat command, before the $x.
So the code should read:
#! /usr/bin/tcsh -f
echo please enter files list
set x = $<
foreach i ('cat $x')
echo $i
end
You have two mistakes in your tcsh script:
Missing cat command in front of the filename in your foreach condition.
Use of straight single quotes(' ') instead of backquotes (``) in your foreach condition.
The following script should work for you.
#!/usr/bin/tcsh -f
echo please enter files list
set x = $<
foreach i(`cat $x`)
echo $i
end
Related
I would like to know how to access the contents of a variety of txt files by passing arguments into shell scripts. I'll have different files and I'm expecting to execute with this command:
./script.sh FileA.txt
What should I put into my shell script so that I can access and manipulate the contents of the files?
I tried this but it outputs 0:
echo "$#"
I also tried these, but both output nothing:
for i in $1
do
echo "$i"
done
echo "$1"
To sum up the contents see this link to understand bash arguments more https://tecadmin.net/tutorial/bash-scripting/bash-command-arguments/ . Also as #Barmar said, to iterate through a list of arguments of unknown quantity use for i in "$#" .
edit
and as #Barmar said, $1 is simply the name of the argument. So echoing $1 will just echo the name.
I don't understand your question fully. Lets assume you have list of file names in a text file "FileA.txt".
And you wanted to run some commands for each file in the "FileA.txt" file.
Can you try below:
for i in `cat $1`
do
echo $i
done
I have prepared a bash script to get only the directory (not full path) with file name where file is present. It has to be done only when file is located in sub directory.
For example:
if input is src/email/${sub_dir}/Bank_Casefeed.email, output should be ${sub_dir}/Bank_Casefeed.email.
If input is src/layouts/Bank_Casefeed.layout, output should be Bank_Casefeed.layout. I can easily get this using basename command.
src/basefolder is always constant. In some cases (after src/email(basefolder) directory), sub_directories will be there.
This script will work. I can use this script (only if module is email) to get output. but script should work even if sub directory is present in other modules. Maybe should I count the directories? if there are more than two directories (src/basefolder), script should get sub directories. Is there any better way to handle both scenarios?
#!/bin/bash
filename=`basename src/email/${sub_dir}/Bank_Casefeed.email`
echo "filename is $filename"
fulldir=`dirname src/email/${sub_dir}/Bank_Casefeed.email`
dir=`basename $fulldir`
echo "subdirectory name: $dir"
echo "concatenate $filename $dir"
Entity=$dir/$filename
echo $Entity
Using shell parameter expansion:
sub_dir='test'
files=( "src/email/${sub_dir}/Bank_Casefeed.email" "src/email/Bank_Casefeed.email" )
for f in "${files[#]}"; do
if [[ $f == *"/$sub_dir/"* ]]; then
echo "${f/*\/$sub_dir\//$sub_dir\/}"
else
basename "$f"
fi
done
test/Bank_Casefeed.email
Bank_Casefeed.email
I know there might be an easier way to do this. But I believe you can just manipulate the input string. For example:
#!/bin/bash
sub_dir='test'
DIRNAME1="src/email/${sub_dir}/Bank_Casefeed.email"
DIRNAME2="src/email/Bank_Casefeed.email"
echo $DIRNAME1 | cut -f3- -d'/'
echo $DIRNAME2 | cut -f3- -d'/'
This will remove the first two directories.
I have this assignment to solve:
"Write a shell script that continuously reads words from the keyboard and
deletes them from all the files given in the command line."
I've tried to solve it, here's my attempt:
#!/bin/bash
echo "Enter words"
while (true)
do
read wrd
if [ "$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).
I want to loop through a path list that I have gotten from an echo $VARIABLE command.
For example:
echo $MANPATH will return
/usr/lib:/usr/sfw/lib:/usr/info
So that is three different paths, each separated by a colon. I want to loop though each of those paths. Is there a way to do that? Thanks.
Thanks for all the replies so far, it looks like I actually don't need a loop after all. I just need a way to take out the colon so I can run one ls command on those three paths.
You can set the Internal Field Separator:
( IFS=:
for p in $MANPATH; do
echo "$p"
done
)
I used a subshell so the change in IFS is not reflected in my current shell.
The canonical way to do this, in Bash, is to use the read builtin appropriately:
IFS=: read -r -d '' -a path_array < <(printf '%s:\0' "$MANPATH")
This is the only robust solution: will do exactly what you want: split the string on the delimiter : and be safe with respect to spaces, newlines, and glob characters like *, [ ], etc. (unlike the other answers: they are all broken).
After this command, you'll have an array path_array, and you can loop on it:
for p in "${path_array[#]}"; do
printf '%s\n' "$p"
done
You can use Bash's pattern substitution parameter expansion to populate your loop variable. For example:
MANPATH=/usr/lib:/usr/sfw/lib:/usr/info
# Replace colons with spaces to create list.
for path in ${MANPATH//:/ }; do
echo "$path"
done
Note: Don't enclose the substitution expansion in quotes. You want the expanded values from MANPATH to be interpreted by the for-loop as separate words, rather than as a single string.
In this way you can safely go through the $PATH with a single loop, while $IFS will remain the same inside or outside the loop.
while IFS=: read -d: -r path; do # `$IFS` is only set for the `read` command
echo $path
done <<< "${PATH:+"${PATH}:"}" # append an extra ':' if `$PATH` is set
You can check the value of $IFS,
IFS='xxxxxxxx'
while IFS=: read -d: -r path; do
echo "${IFS}${path}"
done <<< "${PATH:+"${PATH}:"}"
and the output will be something like this.
xxxxxxxx/usr/local/bin
xxxxxxxx/usr/bin
xxxxxxxx/bin
Reference to another question on StackExchange.
for p in $(echo $MANPATH | tr ":" " ") ;do
echo $p
done
IFS=:
arr=(${MANPATH})
for path in "${arr[#]}" ; do # <- quotes required
echo $path
done
... it does take care of spaces :o) but also adds empty elements if you have something like:
:/usr/bin::/usr/lib:
... then index 0,2 will be empty (''), cannot say why index 4 isnt set at all
This can also be solved with Python, on the command line:
python -c "import os,sys;[os.system(' '.join(sys.argv[1:]).format(p)) for p in os.getenv('PATH').split(':')]" echo {}
Or as an alias:
alias foreachpath="python -c \"import os,sys;[os.system(' '.join(sys.argv[1:]).format(p)) for p in os.getenv('PATH').split(':')]\""
With example usage:
foreachpath echo {}
The advantage to this approach is that {} will be replaced by each path in succession. This can be used to construct all sorts of commands, for instance to list the size of all files and directories in the directories in $PATH. including directories with spaces in the name:
foreachpath 'for e in "{}"/*; do du -h "$e"; done'
Here is an example that shortens the length of the $PATH variable by creating symlinks to every file and directory in the $PATH in $HOME/.allbin. This is not useful for everyday usage, but may be useful if you get the too many arguments error message in a docker container, because bitbake uses the full $PATH as part of the command line...
mkdir -p "$HOME/.allbin"
python -c "import os,sys;[os.system(' '.join(sys.argv[1:]).format(p)) for p in os.getenv('PATH').split(':')]" 'for e in "{}"/*; do ln -sf "$e" "$HOME/.allbin/$(basename $e)"; done'
export PATH="$HOME/.allbin"
This should also, in theory, speed up regular shell usage and shell scripts, since there are fewer paths to search for every command that is executed. It is pretty hacky, though, so I don't recommend that anyone shorten their $PATH this way.
The foreachpath alias might come in handy, though.
Combining ideas from:
https://stackoverflow.com/a/29949759 - gniourf_gniourf
https://stackoverflow.com/a/31017384 - Yi H.
code:
PATHVAR='foo:bar baz:spam:eggs:' # demo path with space and empty
printf '%s:\0' "$PATHVAR" | while IFS=: read -d: -r p; do
echo $p
done | cat -n
output:
1 foo
2 bar baz
3 spam
4 eggs
5
You can use Bash's for X in ${} notation to accomplish this:
for p in ${PATH//:/$'\n'} ; do
echo $p;
done
OP's update wants to ls the resulting folders, and has pointed out that ls only requires a space-separated list.
ls $(echo $PATH | tr ':' ' ') is nice and simple and should fit the bill nicely.