Questions about shell scripts, executable files that are interpreted by a shell (bash, zsh, etc.).

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0
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19 views

Why are my variables not reset to zero?

In the below loop, I try to reset the values of two variables (totalentries and totalusedbytes) to zero, but I can see from the results that it never happens. Thus each loop continues to add to the ...
2
votes
3answers
37 views

Does it make a difference (e.g. performance-wise) if I execute a command from a bash script (vs the command line)?

Is there any difference between the following (e.g. performance-wise): $ make && cp bin/myexecutable inputfile.txt $workdir && cd $workdir $ <series of sed commands to modify ...
1
vote
2answers
46 views

How to print file content *and delete printed content* from file?

In Linux bash shell, How can I print file content and delete printed content from file? I have a program writing texts to a file repeatedly. On a Linux shell prompt, I want to print the contents of ...
2
votes
2answers
73 views

How to remove duplicate files using bash

I have a folder with duplicate (by md5sum (md5 on a Mac)) files, and I want to have a cron job scheduled to remove any found. However, I'm stuck on how to do this. What I have so far: md5 -r * | ...
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0answers
33 views

Convert file pattern in Unix

I have a file with content as below 31/01/2014 1234 2234 4567 3321 ...n Need to write a shell script to convert the above file as below: DD_Date='31/01/2014' ...
1
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3answers
36 views

CSV Units Conversion

I've got a CSV file that looks like the following: miami,20,in lansing,2,cm austin,3,mm chicago,5,miles phoenix,2,feet The first field is the name, the next field is the numeric value and the third ...
1
vote
1answer
42 views

Write text on last line of document [duplicate]

If I have this document aaa bbb ccc And I want to add " ddd" on the last line. My document should look like this: aaa bbb ccc ddd How can I do this? If I prefer awk or sed but ...
0
votes
1answer
52 views

tar unused files then delete them

I have folder with subfolders and sessions logs. I need some commands or script to tar this folder without usage files and then delete it. I have this construction, but I'm not sure if this leave ...
2
votes
1answer
89 views

grom() keyword in bash throws unexpected '(' token

I'm not entirely sure why I'm getting the error in my .bash_profile syntax error near unexpected token `(' when I use the keyword grom() for my function. I wanted to create a bash function that ...
1
vote
1answer
53 views

Brace expansion not working in a script

for i in {1..40} do echo $i done I got {1..40} and I would like to have something like 1 2 3 and so on so I can use the variable i inside a command's parameter.
1
vote
3answers
72 views

Find result used in if statement

How can I use the result of a find command in an if statement and compare with true or false? Something like this: if [ `find . -name test.txt -size 156c`="true" ]; then echo Found; fi This is ...
0
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1answer
36 views

User Input Bash Script

I am trying to make a Bash Script that has 4 choices and prompts the user to select an option. Each option corresponds to a Linux Command operation. Can someone give me a bash example on how could ...
0
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2answers
41 views

Its possible use special characters in a shell function name?

I have to create the function in shell script, that function name must contain the special characters. like >() { echo $1 $2 } Here my function name is >, If its ...
1
vote
2answers
30 views

Read file remove spaces and store in array

I have a file with the following content: list: blue,none red,none orange,plot baseball , none university,none school,none desk,plot monitor,none earphone,none I need to read this file, ...
0
votes
0answers
28 views

How to get and print a user's public IP address in a Shell Script? [duplicate]

I've just completed a lengthy installation script that deploys a Ruby on Rails application unto web servers. At the end of this script, I'd like it to print something along the lines of: "Installation ...
0
votes
2answers
45 views

Adding 1 string to end of file, Even when ran multiple times to change MD5

I need to change the md5 of my files, Sometimes once, sometimes multiple times. A friend gave me this script to add a string to the end of the file but i think i may be adding it multiple times when i ...
1
vote
1answer
31 views

Search for text inside java command output

I have a folder which have multiple Jar files. * dummy.jar * myjar-xx.jar * myjar-yy.jar Using find, I need to find first file starting with "myjar" Now, I want to grep the contents of ...
4
votes
1answer
45 views

Why does 'jobs' always return a line for finished processes when run in a subshell within a script?

Normally, when a job is launched in the background, jobs will report that it is finished the first time it is run after the job's completion, and nothing for subsequent executions: $ ping -c 4 ...
2
votes
1answer
23 views

how to connect automatically to a saved list of networks

I want to make my Debian laptop connect automatically to a list of stored WiFi networks in a text file that have the syntax SSID:password, using a non graphical way (script or config). These networks ...
0
votes
1answer
38 views

What's a way to get the first network interface using grep in ifconfig? [on hold]

Just trying to figure this out for a System Administration introduction course, and I can't seem to get it.
0
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2answers
98 views

Shell script to execute psql command [on hold]

I want to make an automated script to make a database user and password in Postgresql and also import some databases. When i execute my script bellow it stops somewhere and when i log out (CTRL+D or ...
-1
votes
0answers
41 views

No Such file or Directory 4 [on hold]

throw the script posted in this question link syntax error near unexpected token `)' I get this error: test.txt: No such file or directory 140308719470240:error:02001002:system library:fopen:No ...
0
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1answer
43 views

Can a command in a shell pipeline determine the tty characteristics of its context?

I have a bash script that columnizes a list of items. By default it will guess at the number of columns to output, based on the terminal width as reported by stty size. But when the script is in a ...
1
vote
1answer
152 views

how to check the string is Null or not in shell script? [on hold]

I had a script like this #!/bin/bash line="hello" if [ -z $line ] ; then echo "String null" fi This will work properly, but when I give the lineas follows ...
0
votes
1answer
24 views

sepration of files on the basis of there name

I have a folder containing lots of files like 3 lac plus files. I have to separate them according to their names in three different folders. e.g. a few names are: 7msf_stem_0_mcannotate.pdb ...
4
votes
4answers
325 views

How to fill a file with a stream from /dev/urandom with a specified number of lines ?

I am trying to fill a file with a sequence of random 0 and 1s with a user-defined number of lines and number of characters per line. the first step is to get a random stream of 0 and 1s: cat ...
1
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1answer
31 views

Using parameters in a script

I usually use the find command to automatically copy certain multimedia files from directory A to directory B. I use the following command: for f in `find ./ -name "*.mkv" -mtime -24h`; do cp $f ...
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0answers
23 views

Inserting a text file into a script using cyg-win- did i not claify it well enough? [on hold]

I am writing a script that checks for directories, if they are not there then it is to create them. In two of the directories i need to insert a text file. One of the files has eight comment line and ...
1
vote
1answer
35 views

Test for open TCP port in bash script

I want to delay the script execution until a certain server process is ready, which it is once it accepts incoming TCP connections. How do I test if a local TCP port is open (I get a SYN/ACK answer)? ...
1
vote
2answers
20 views

Script using sudo works from a terminal but not from a desktop shortcut

I create small script to mount encfs filesystem. just like this: #!/bin/bash kdialog --password "Wprowadź hasło do SSH lub ENTER żeby rozłączyć:" > /home/maciek/Pobrane/pass-1 sudo encfs -S ...
0
votes
2answers
47 views

Input in bash script

I have a script like this: for i in *.TF; do my command $i done The problem is, each command line needs a same input (in this case: /PS) how can I do this? I have tested some methods like: /PS | ...
-1
votes
1answer
29 views

AWK and Bash Scripting [duplicate]

How to use a value of a variable in awk? Something like this: filename = "test.txt" ls -l | awk '{ if ($9 == filename) print("File exists")}' I can't use $ in awk to access the value of ...
0
votes
1answer
20 views

Cron start script twice

I have a backup script which sends my snapshots to a off-site location. 0 0 * * * /root/backup/backup_incremental >> /root/backup/test.log For some reason my PID file which should stop the ...
2
votes
2answers
86 views

How to delete old backups based on a date in file name?

I have a daily backups named like this: yyyymmddhhmm.zip // pattern 201503200100.zip // backup from 20. 3. 2015 1:00 I'm trying to create a script that deletes all backups older than 3 days. The ...
1
vote
1answer
52 views

Bash: using both way redirections in a shell script

I'm writing a shell script to compress and backup certain files. This will compress and move large files with sizes up to 4 GB. I'm having trouble with this line: gzip < $filelocation > ...
3
votes
3answers
86 views

Delete folders which not match a list

I need practical example how get rid folders which are not in the list in Linux. So i do not need to compare its contents or md5sums, just compare folders names. For example, one folder has few ...
1
vote
1answer
46 views

How to Prompt the user to press Enter to Exit in terminal so that the terminal doesn't close automatically?

Here is my Port.sh file echo 'Give me a maximum of 5 seconds to run please.' lsof -i | grep Xvnc | grep ESTABLISHED | grep $USER lsof -i | grep $USER | grep Xvnc | grep -o -P '(?<=:).*(?=->)' ...
3
votes
1answer
48 views

How to poweroff headless machine using a script

I have a Java application that starts automatically when the headless machine (Ubuntu 14.04 Server) boots and runs as a user. When the application is finished I need it to execute a script to ...
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votes
3answers
57 views

How to Show your main “shell” that you use.? in UNIX

How to Show your main “shell” that you use.? in UNIX is this command right ps -p$$ or if there is a different way? thank you
1
vote
1answer
35 views

Indented here document causes a syntax error

I have the following code fragment in my shell script and have a bug that I can't seem to pin down a reason for despite some research. When I run the code as below the script exits with a message ...
3
votes
2answers
102 views

Nested 'awk' in a 'while' loop, parse two files line by line and compare column values

I need some help with a combination of awk & while loop. I have two simple files with columns (normal ones are very large), one representing simple intervals for an ID=10(of coding ...
0
votes
1answer
19 views

mkvmerge in a bash script does not execute

I have made a script which does mux a videofile, multiple audiofiles and multiple subtitles into one .mkv. the script tries to run: "/usr/bin/mkvmerge" -o "test.mkv" "--default-track" "0:yes" ...
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votes
3answers
38 views

Error in `for` loop in `if… else` conditions

Hi guys I am new in writing bash script. I have a task to do. I have a file in which node name and IP addresses are updated, I have to make each file of those nodes which are not in our required ...
1
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0answers
20 views

Avoid “Shared connection to <host> closed” messages

I'm managing a lot of drupal sites, and trying to automate some stuff using drush. Drush run locally calls drush on the remote host via ssh using options specified in the config for the site alias. ...
1
vote
3answers
51 views

How can I create a relative symlink given a relative path?

I would like to programmatically find the directory depth of a relative path. So for example the depth of test/dir/hello is 3 More specifically I would like the directory depth so that I can create a ...
4
votes
1answer
18 views

Shell script: filter list of .pdf files, to exclude those with a .tex source file

I have a linebreak-separated list of file paths, all to pdf files. I would like to filter out all those which have a corresponding *.tex file in the same directory (and so can be presumed ...
2
votes
5answers
82 views

How to create a script that can't be easily exited

How would I create a script that does not respond to Ctrl-C? This should also prevent any processes launched by the script from being killed (I'm trying to keep apt-get upgrade from being killed). (I ...
2
votes
1answer
35 views

Updating config files within the script that references them?

I have no problem adding config files to a given script, but automatically updating them is another matter. In this instance I'm providing a few variables to a script, and I'd like the script to be ...
1
vote
0answers
20 views

How to make svn save credentials when --non-interactive

I'm trying to get svn to save my https username+password to ~/.subversion from within an automated script. I can pass creds on the command-line but I do not want to be prompted about whether to save ...
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votes
0answers
34 views

How can I encrypt specific words in a text file with a bash script? [closed]

I want to encrypt same words in a text file and I want to know how I can do it in bash. For example, if the file contains: The employee Kim Van, his registration number is ID721 he is work in the ...