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

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4
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5answers
367 views

Join two files, matching on a column, with repetitions

How can I get two files A and B, and out put a result like this: File A: 001 Apple, CA 020 Banana, CN 023 Apple, LA 045 Orange, TT 101 Orange, OS 200 Kiwi, AA File B: 01-Dec-2013 01.664 001 ...
-2
votes
1answer
451 views

automatic capturing top output by cronjob CENTOS 6.5 x86_64

I have this command: top -n 14400 -a -b -d 1 > /toplogfile.txt I want to make a script which is run by cron every day to capture top output, and if it is possible gzip the output file after the ...
1
vote
1answer
486 views

How would I detect a non-login shell? (In Zsh)

I want to create a script that runs when a Zsh instance starts, but only if the instance is: Non-login. Interactive I think I'm right to say .zshrc runs for all interactive shell instances, ...
1
vote
3answers
1k views

How to get numbers by using regular expression, but only last one

In this example I can get 00. expr match "00 foo 99.jpg" '[^0-9]*\([0-9]\+\).*$' I want to know how to get last number from string, in this case 99 by using regular expression. The string may ...
2
votes
1answer
2k views

Changing text color in c-shell

I can change the text color in the terminal permanently by adding this: export PS1="\e[0;31m[\u@\h \W]\$ \e[m" to the .bashrc file. Now I have to go into cshell, what is the corresponding way?
0
votes
0answers
109 views

Is there a difference between `command rspec` and `rspec`?

I want to call bundle exec rspec if Gemfile exists in current directory, and if it doesn't exists, call rspec itself. So I wrote like this. function rspec() { if [ -e 'Gemfile' ]; then echo ...
5
votes
5answers
368 views

A shell script to write selected fields to a single line

I have a log file trace.log which prints the time stamp, thread name and Transaction method and transaction ID as below. 2014-01-23 15:50:41,724 [catalina-exec-35] INFO TRANSACTION getConnection ...
0
votes
3answers
165 views

How can I add a script to embedded Linux

I have a script (let's say Hello World), that I want to include to my embedded Linux. I'm using Buildroot and want to start the script in Busybox. But because I'm cross-compiling for the target I'm ...
1
vote
1answer
43 views

Where can I find documentation on shell script syntax for using a regex within a variable construct?

I'm debugging a shell script (which I didn't write) that contains this loop: read line < "$pid_file" for p in $line ; do [ -z "${p//[0-9]/}" -a -d "/proc/$p" ] && pid="$pid $p" done ...
0
votes
1answer
977 views

shell script - echo command not printing in proper sequence

I have the following testfile.txt: string1 1 string2 2 string3 3 string1 2 string2 4 string3 6 string1 3 string2 6 string3 9 I have the following script: #!bin/sh ...
0
votes
0answers
38 views

Bash script to identify which init system the system currently using [duplicate]

I have to create a script that will mount my /usr folder as aufs. I compressed it using squashfs. I've managed to install a working systemd init in ubuntu which I am currently using. Because the ...
0
votes
1answer
150 views

Debian one time setup after reboot

I have a pre-configured server based on Debian with some services. I, now, need to deploy it in different networks. Is there any solution to run a one time script after reboot which asks some ...
0
votes
1answer
218 views

shell script - reading from standard input versus a file

I have the following input file in.txt: a b c a b c I have the following script test.sh: # display unique rows while read line do echo $line done < $(cat "$@" | sort | uniq) # display all ...
3
votes
0answers
564 views

Number comparisons in BusyBox ash

I have the following script that extracts data from the EXIF command on my BusyBox ash-based system. I parse the date tag from the end of the file and use case as a final check to ensure the format ...
1
vote
2answers
782 views

Cygwin - Shell Scripting (eval and echo)

I have the following file f1.txt: A=0 A=\`expr $A + 1\` and the following script file s1.sh for line in $(cat testfile.txt) do echo "$line" # eval $line done echo $A When I run the ...
3
votes
2answers
1k views

Bash Script To Find Debian Release Number from /etc/debian_version

The following is what I'm currently using for testing the version of Debian. Instead of doing it this way, can I make it more succinct? #!/bin/bash VERSION=NONE if [ $(cat /etc/debian_version) == ...
3
votes
1answer
149 views

Can someone clarify this Bash script

I'm learning something about Bash scripting, and I came across this example: The task is to write a Bash script that reads a file, given with the first argument, pulls out those records that have the ...
1
vote
1answer
363 views

removing data from txt file

I have a comma-delimited giant file that was exported from a database. The file has this format Date,n1,n2,n3,n4,n5,n6,color,type,reference 10-Jan-2000,344,13,21,2,55,3,"rose garden" ,3444,32 ...
2
votes
3answers
914 views

To assign variable from a file separated by delimiter

I have a text file with datas as below separated by delimiter: 1000:Tom:user1 1002:Jerry:user2 1003:Victor:user3 1004:Jason:user4 I need to run a while loop (any loop) to fetch details from first ...
3
votes
3answers
889 views

Bash script to delete a file called index.html recursively

I need a bash script (not sure how to write the actual .sh file) which I could set to be run by cron every minute and that would delete files with the name index.html that are in a specific directory ...
4
votes
3answers
1k views

Help Shell script to pass variables to rsync

I'm trying to create a simple wrapper shell script for rsync. When I send file names to my script, rsync can never seem to identify the correct location. The file names have spaces in them. I've tried ...
0
votes
2answers
14k views

Shell scripting: -z and -n options with if

I have a shell script where we have following lines if [ -z "$xyz" ] and if [ -n "$abc" ], but I am not sure what their purpose is. Can anyone please explain?
2
votes
1answer
2k views

“stdin: is not a tty” mails for running scripts as cron jobs

I have several shell scripts (bash) which are started by cron. Every time a script is executed I get an email saying "stdin: is not a tty". Can someone please tell me how to fix this? All scripts run ...
5
votes
2answers
3k views

How to append multiple lines to a file without last newline?

I have a very long string that is split in chunks. I want to append them to a file without putting the newline character using bash. Example: First append cat >> abc.sh << EOL echo "bla ...
0
votes
1answer
56 views

Prepare a computer for being firstly used in my home network with a BASH script is possible?

I need a script that detects the computer joined the same home network and standardize its folder structure. For example If there's A, B and C computers in a network which are configured to have a ...
4
votes
1answer
85 views

What's the difference between sh script and sh < script

What's the difference between sh myscript and sh < myscript I played around and they seem to have the same effect. Are they equivalent?
6
votes
2answers
498 views

Expansion of a shell variable and effect of glob and split on it

This post actually contains two separate questions but I think grouping them together will give some more context. I have gone through this question on quotes around variables but I do not quite ...
2
votes
1answer
276 views

Bash:source files without fullpath?

if I source the script file without pre-path definition, it does not work. What is happening below? I have got a go1 function in the file simply printing $PWD. $ bash --version GNU bash, version ...
1
vote
1answer
39 views

Problematic quotations

#!/bin/ksh typeset FILE_SIZE1=$(stat -f '%z' test.txt); typeset -r BK_STATARGS="-f '%z'" typeset FILE_SIZE2=$(stat ${BK_STATARGS} test.txt); echo without arg var ${FILE_SIZE1} echo with arg var... ...
1
vote
2answers
568 views

Script to su -c into a screen is not working as intended

I'm working on a script that will allow me to load up a screen from a user via sudo and su -c. However, when I use it, it will just show the shell of the user: sudo su -c "script /dev/null; screen -r ...
2
votes
2answers
202 views

Help with 64-bit integers in scripts?

Maybe I'm overthinking this (although I don't think I am)....or maybe there's a neater way of solving my problem ? I have a requirement that if a file is larger than 1GB, it gets split into smaller ...
0
votes
0answers
20 views

Multiply 2 array index variables shell programming [duplicate]

How do i multiply 2 array index variables given the following foo=(1 2) bar=(0.1 0.2) foobar=$((foo[1]*price[1])) # this is wrong echo "$foobar" Current output : 0 Correct/Expected output : 0.4
2
votes
1answer
217 views

How to FILTER the files with filename and then DELETE the OLDEST file from there? [duplicate]

I create and keep the following automated backup files e.g.: fruits_29-12-2013.gz fruits_30-12-2013.gz fruits_31-12-2013.gz sweets_01-12-2013.gz sweets_02-12-2013.gz sweets_03-12-2013.gz .. ...
3
votes
1answer
442 views

Compare users out of an array with /etc/shadow file

I want to check for all users who do not have a password set. For example, a user with the following entry in /etc/passwd test01::15164: ...* has no password set. I would like to list all such ...
2
votes
2answers
218 views

Show a sliding window of output from a program

I want to run a command (rsync -av) and only display 10 lines of output at any time. I have found a similar post, but I don't want to redirect it to a file. I want the output to be displayed ...
3
votes
3answers
255 views

USB device to be detected at the “same” /dev point always?

In Linux (actually I'm with CentOS v6.5), whenever I plug in my USB Terminal/Character Device (some kind of USB Adapter) for the first time (after booted), it is detected at: /dev/ttyUSB0 But ...
1
vote
1answer
202 views

Does cron impose some limitations to types of commands and privilege of execution? [duplicate]

I've experienced an issue where some of my scripts run perfectly fine when I call them manually, but these same scripts when called as cron jobs via cron don't seem to work at all. So my question: ...
4
votes
2answers
1k views

How can I trigger an event in shell script when an USB device is removed?

I need to do some actions when a specific USB device is removed/added. I need a fast response on the order of milli-seconds. How can I do this in a shell script?
3
votes
1answer
89 views

Common flag designations and standards for shell scripts and functions

I have been adjusting to using GETOPT and GETOPTS in my shell scripts and custom functions to enable me to use the functions that I create more flexibly. After using a number of UNIX functions I have ...
2
votes
3answers
111 views

Code duplication in a shell script

My bash script (lets call it myscript) takes input either from stdin (pipe), or form a regular file (if filename was provided as an argument) a) someprog | myscript or b) myscript file.txt ...
5
votes
2answers
3k views

Is it possible to execute a script as first at shutdown/reboot on Debian?

I am currently trying to register a script (located in the /etc/init.d) in a way that makes this script being executed as the first script/programm at shutdown/reboot (change to running level 0 or 6). ...
4
votes
3answers
2k views

How to output to screen overriding redirection

Is it possible, within a shell script, to write to the screen while STDOUT and STDERR is being redirected? I have a shell script that I want to capture STDOUT and STDERR. The script will run for ...
0
votes
5answers
871 views

On executable files in Linux [closed]

It is said that in linux, unlike Windows, there's not a clear border between executables and other files. Well, in Windows, I write a C++ program, then it is precompiled, compiled and then linked to ...
5
votes
5answers
6k views

How to parse ISO8601 dates with linux date command

I'm trying to use the date command to generate a file timestamp that the date command itself can interpret. However, the date command does not seem to like its own output, and I am not sure how to ...
3
votes
2answers
3k views

Using a variable in a regex

How can I use a variable string in a regular expressions while read line do if [[ line =~ *"$key"* ]]; then echo line fi done < "$filename" $key is a string ...
0
votes
1answer
67 views

Curl command help

I'm trying to connect to a internal tool UI, then login and later logout. The homepage is having 3 drop-down options and 2 tabs where we need to enter the IP & Port and then connect. Once ...
1
vote
2answers
146 views

Merging two different files with conditions

I have two different files as shown below. Content of a.txt: HDR|1|||||||||| DTL|@||||||||||| TLR||||||||||||| HDR|1|||||||||||| ...
1
vote
2answers
105 views

Mailing out a customised content based on specific search in a logfile

Using below test.sh, I am getting result in dump.txt as below: test.sh: #!/bin/bash #"Maxl-script" zone starts..... essmsh -l admin password -s localhost -i << EOF spool on to 'dump.txt'; ...
0
votes
2answers
187 views

How to Lookup the values of an index values from a big data file?

I have a data file (data_array.txt in the example) and index file, index.txt, at which I want to extract the data from the data file that have the same ID in the index file and store in to a new file, ...
2
votes
5answers
2k views

Cut and transpose some lines of a file

I have 1344 rows of data column. I want to form 32 row by 42 columns from my input data file. I want to cut the first 42 row and paste to one raw of 42 column data and continue down likewise. My data ...