Hi I'm starting to learn how make and use shell scripts, one the shell scripts I want to make is a shell script that takes in a string input from a user that is asking for a file name and it reports whether the file is present or not. I unsure of what to do.
Here's what I've written:
#!/bin/bash
read string1
echo${#string1} ; grep
I don't know what to do after typing in grep.
Please help.
grep looks for a string that occurs in the file's contents. If you just want to test whether a file with a given name exists, grep is not necessary.
#!/bin/bash
read string1
if test -e ${string1}; then
echo The file ${string1} exists
fi
will do.
[copied from comment to answer as suggested by #glenn jackman]
Use the file test operator instead of grepping for the name:
#!/bin/bash
printf "Enter a filename: "
read string1
if [[ -f "$string1" ]]; then
echo "The file '$string1' exists."
else
echo "The file '$string1' does not exist!"
fi
Don't forget to quote your variables so that names with spaces and odd characters are parsed correctly.
$ bash test.sh
Enter a filename: hash.pl
The file 'hash.pl' exists.
$ bash test.sh
Enter a filename: odd file.txt
The file 'odd file.txt' exists.
$ bash test.sh
Enter a filename: somefile
The file 'somefile' does not exist!
Related
I have written a small script that will take the users input and then generate the md5sum values for it
count = 0
echo "Enter number of records"
read number
while [ $count -le $number ]
do
echo "Enter path"
read path
echo "file name"
read file_name
md5sum $path"/"$filename #it shows the md5sum value and path+filename
((count++))
done
How can I pass these values ( path,file name, and md5sums ) to CSV file. ( assuming the user chooses to enter more than 1 record)
The output should be like
/c/training,sample.txt,34234435345346549862123454651324 #placeholder values
/c/file,text.sh,4534534534534534345345435342342
Interactively prompting for the number of files to process is just obnoxious. Change the script so it accepts the files you want to process as command-line arguments.
#!/bin/sh
md5sum "$#" |
sed 's%^\([0-9a-f]*\) \(\(.*\)/\)?\([^/]*\)$%\3,\4,\1%'
There are no Bash-only constructs here, so I switched the shebang to /bin/sh; obviously, you are still free to use Bash if you like.
There is a reason md5sum prints the checksum before the path name. The reordered output will be ambiguous if you have file names which contain commas (or newlines, for that matter). Using CSV format is actually probably something you should avoid if you can; Unix tools generally work better with simpler formats like tab-delimited (which of course also breaks if you have file names with tabs in them).
Rather than prompting the user for both a path to a directory and the name of a file in that directory, you could prompt for a full path to the file. You can then extract what you need from that path using bash string manipulations.
#!/bin/bash
set -euo pipefail
function calc_md5() {
local path="${1}"
if [[ -f "${path}" ]] ; then
echo "${path%/*}, ${path##*/}, $(md5sum ${path} | awk '{ print $1 }')"
else
echo "
x - Script requires path to file.
Usage: $0 /path/to/file.txt
"
exit 1
fi
}
calc_md5 "$#"
Usage example:
$ ./script.sh /tmp/test/foo.txt
/tmp/test, foo.txt, b05403212c66bdc8ccc597fedf6cd5fe
Below is a snapshot of a file called ".bashrc":
I'm beginner in bash and What i'm trying to do in bash is to check if the last two lines inside the file exist and correctly written like for example :
if [ export PATH=/opt/ads2/arm-linux64/bin:$PATH ]
then
echo "found system variable lines"
else
echo "systemvariables do not exists, please insert it in .bashrc"
fi
However, this doesn't seem to be trivial since the tow lines to be shared are not pure string lines.
Thanks in advance
Use grep to find stuff in file contents.
# if file .bashrc contains the line exactly export PATH=....
if grep -Fxq 'export PATH=/opt/ads2/arm-linux64/bin:$PATH' .bashrc ; then
echo "found system variable lines"
else
echo "systemvariables do not exists, please insert it in .bashrc"
fi
Read man grep and decide if you want or not the -F and -x options in grep. For sure research and learn regex - I recommend regex crosswords available on the net. Research also difference between single quoting and double quoting in shell. Remember to check scripts with http://shellcheck.net
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 am a Unix/Linux shell script newbie and I have been asked to look at a script which contains the lines below. The following details in this question are vague but the person who wrote this code left no documentation and has since demised. Can anyone advise what they actually do?
There are two specific pieces of code. The first is simply line source polys.sh where polys.sh is a text file with contents:
failure="020o 040a"
success="002[a-d] 003[a-r] 004[a-s] 005[a-u]
Representing various parameters, I think, to do with the calculations the shell script performs. The nature of the calculations is, I am told, not important because the aim is to just get the script running.
The second piece of code is below and the relevant lines are delimited by Start and Stop comments. What I can tell you is that: $arg1 is blank, $opt1 is also blank, $poly is the path and name of a text file and ./search I believe to be a folder.
if [ $search == "yes" ]
then
# Search stage for squares containing zeros
#
# Start.
output="$outputs/search/"`basename $poly`
./search $opt1 $arg1 < $poly 2>&1 | tee $output
if tail -n1 $output | grep -v "success"
# End.
then
echo "SEARCH FAILURE" >> $output
continue
fi
# Save approximations
#
echo -n "SEARCH SUCCESS " >> $output
cat /tmp/iters >> $output
cp /tmp/zeros $inputs/search/`basename $poly`
else
echo "No search"
fi
EDIT Initial disclaimer as advised by Mr. Charles Duffy:
The below explanations assume you won't hit expansion-related bugs; please correct your code as advised by shellcheck.net to be assured that these explanations are correct
source polys.sh includes the code from the script polys.sh, which is a file in the same folder as the file sourcing it (hence just the filename, without its path).
Within that file:
failure="020o 040a"
success="002[a-d] 003[a-r] 004[a-s] 005[a-u]"
are two variable declarations; the variable $failure is set to "020o 040a" and $success to "002[a-d] 003[a-r] 004[a-s] 005[a-u]". As the file was sourced, these two variables are available in your script (do echo "$failure" and echo "$success" to see for yourself).
output="$outputs/search/`basename $poly`" has two parts to explain:
"$outputs/search/"
sets the variable $output to "$outputs/search/", i.e., to the value of the variable $outputs, appended by the string "/search/".,
`basename $poly`
anything in backticks is a command substitution, which interprets and runs the command returning its output, and the command basename $poly gets the base file or folder name from $poly, if it is a file path (e.g., basename $poly for poly="/dev/file.txt" yields file.txt); the output is appended as a string. to "$outputs/search/".
./search $opt1 $arg1 < $poly 2>&1 | tee $output is two commands, separated by a pipe |:
./search $opt1 $arg1 < $poly 2>&1
runs the executable file ./search (./ is shorthand for the current script's directory) with two arguments, $opt1 and $opt2 variables. $poly is the variable name which should represent a file path, of which the file path has its content redirected to the command (using <). The output of all errors (stderr, as 2) is redirected (>) to the standard output (stdout, or &2, the ampersand represents this is a file descriptor, not a file path, otherwise it would redirect output to a file named 2).
tee $output
tee pipes outputs stdin to stdout and to arguments as file paths. So tee "/home/nick/output" would save the stdin to a file at "/home/nick/output", as well as the stdout.
if tail -n1 $output | grep -v "success"
tail -n1 $output
gets the last line of the file at the "$output" variable's value.
grep -v "success"
searches for any non-match (-v inverts the match) in the last line from tail -n1 of "success" in a line (e.g., if the last line is "fail", it would pass the if statement as it does not contain "success")