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

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4
votes
3answers
833 views

Linux command line that will fail if any standard out is produced

Is there a simple utility which I can pipe output to on Linux that will: Return a success code if there is no output on standard out (and / or standard error). Return a failure code if output is ...
4
votes
1answer
7k views

error handling in expect?

I am just improving my quetion becasue i have acieved so far upto this: set username [lindex $argv 0] set password [lindex $argv 1] set hostname [lindex $argv 2] if {[llength $argv] == 0} { ...
4
votes
1answer
719 views

Printing colored text using script

When I type below command in the shell I get the OUTPUT in green color. Command echo "\033[32mCONNECTING TO abpwrk\033[m"; Output(in green color) CONNECTING TO abpwrk But if I use the same ...
4
votes
2answers
2k views

Set alignment of numeric columns when columnating data

I use column -t to format data for easy viewing in the shell, but there seems to be no option to specify column alignment (e.g. align to the right). Any Bash one-liners to do it? I have arbitrary ...
4
votes
2answers
98 views

Extracting queries from log file that do not include banned lines

I have a log file that looks something like the following: query1 startQuery query1 do something query1 do something else query2 startQuery query1 do something banned query2 do something query3 ...
4
votes
1answer
22 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 ...
4
votes
2answers
74 views

Use lines in a file to produce string and file name

I have a file, foo.txt, that has a folder name on each line: folder_1 folder_2 folder_3 And I'd like to do something like this: cat foo.txt | xargs -I {} echo 'function {}() { return stuff; }' ...
4
votes
3answers
107 views

How can I find and replace only if a match forms a whole word?

My script is: n="y" while [ "{n}" = "y" ] if [ $n == "n" ]; then break; fi echo "n is $n" do read -p "Enter the word to find = " word read -p "Enter word to replace = " replace ...
4
votes
1answer
85 views

Unix: Problem with cmp command

Let me give you an idea of what I am doing. I am running a script that is doing basic OS processes for two systems Linux and SunOS. Well the first directory it runs is called sol0. The script puts ...
4
votes
2answers
98 views

status check for sleep command

I have run sleep command in background as follow , How can I know the status of execution ..? Command sleep 2d ; find /home/disk1/ -exec touch {} \; & How can I know that its executed for 1 ...
4
votes
1answer
386 views

Restricted ssh remote execution with arguments

I need to enable remote execution of a shell script on a server, but deny all other access. The script is a toggle that accepts a single parameter (on/off/status). This comes close to answering my ...
4
votes
1answer
391 views

Default to “Execute” when double-clicking on a shell script in PCManFM

Is it possible to get an executable to execute by default? What I mean is this. I have an .sh file, which if I click on twice, it will show me this: If I then click Execute, it does the right ...
4
votes
1answer
573 views

Run script after desktop loads

I'm running a script that changes files and installs things and what not on a SUSE computer. One of the scripts that gets run with my script, reboots the computer and when the computer loads back up ...
4
votes
2answers
1k views

Find files newer than another file within each subdirectory

I have a folder structure like this /Class/Student/Unit/files Each Unit folder contains a file MarkSheet* that I update when I mark a students work. I need a script that tests if the student has ...
4
votes
3answers
1k 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 ...
4
votes
2answers
727 views

Exiting out of an infinite reboot loop in startup (rc.local)

I am creating a startup script (called from rc.local) in Debian Squeeze. The startup script checks for a variable value from a file, decrements the variable and writes it back to the file, then if the ...
4
votes
2answers
160 views

Dealing with script interruption

I need to iterate over between 120k and 500k files. find handles this well. find $PWD -type f -path "fragments/*.pdbqt" For some reason I want to list the same set of files again, in the same ...
4
votes
1answer
95 views

Transform directory structure

I have the following folder structure root folder |-al2 |- GER.zip |- ENG.zip |-ww |- GER.zip |- ENG.zip and so on. The folder names are random strings. I want to sort the files in ...
4
votes
1answer
740 views

In a script, check if standard input comes from a file or pipe

I know this has been poorly covered previously, but those answers either lack explanation or don't apply. Basically at some point my scripts needs check if a file is specified, if it was it will be ...
4
votes
4answers
7k views

How can I check if mysql is installed using a bash script?

I need to check if mysql is installed from within a bash script. What would be an efficient way of doing that? I thought I could do this: if [ ! -f `which mysql` ] ; then echo "foo" fi But I ...
4
votes
4answers
1k views

script for logging all the stats for a particular process

I want to monitor CPU usage, disk read/write usage for a particular process, say ./myprocess. To monitor CPU top command seems to be a nice option and for read and write iotop seems to be a handy ...
4
votes
2answers
12k views

Wait for process to finish before going to the next line in shell script

I have a script I made to create a backup. I need to make sure the backup is ready before it runs the /home/ftp.sh command. How can I do so? I use CentOS 5.6 #!/bin/bash tar -Pcf ...
4
votes
5answers
144 views

sudo in non-interactive script

I have a script that executes three functions: A && B && C. Function B needs to be run as a super-user, while A and C doesn't. I have several solutions but neither of these is ...
4
votes
2answers
90 views

Replace string in a file with another where both are saved in variables

I want to replace a string found in a file with another string, but both have a special character (in this example it is a . char) e.g 1.0 and 2.0. So this is the command currently used: sed -i ...
4
votes
1answer
134 views

Is there anything equivalent to getch() in ksh?

I am writing a script in Korn Shell, where at one statement I want something like getch() used in C. I want my while loop to be exited, if it sees that I have pressed ESC in Keyboard. For eg. while ...
4
votes
3answers
1k views

Add text with echo but start with new line if file not empty

I'm trying to create next script echo "#!/bin/sh" >/script echo "del x.txt" >>/script witch is ok if /script file is empty, if not - will append first line to last text #!/bin/sh del ...
4
votes
1answer
189 views

inotifywait - get old and new file name when renaming

I'm looking for a reliable way to detect renaming of files and get both old and new file names. This is what I have so far: COUNTER=0; inotifywait -m --format '%f' -e moved_from,moved_to ./ | while ...
4
votes
6answers
716 views

reading a list of lines from a file writing output to a utility

I have a file with a list of lines I want to read from another file. I want to output those lines to a utility (grep) that lets me read the entire line and pull information from it. The file with the ...
4
votes
1answer
61 views

Memory consumption of a script

Is there way to check the memory (physical & virtual) consumption of a script, of course in the moment of its execution. Calculating the used memory minus the used memory before and after the ...
4
votes
1answer
172 views

measure amount of data read from /dev/random

background I have written a collection of bash scripts (most of them in German only yet but if you are interested; download the archive not the single scripts) which help users create high-quality ...
4
votes
1answer
2k views

How to strip color codes out of stdout and pipe to file and stdout

I have a program that uses printf with some tput mixed in it and I'd like to pipe the output to stdout as well as a file. I'd prefer to use sed since I don't want any unnecessary dependencies on my ...
4
votes
1answer
285 views

How Can I Automate the Change between a Python Script and a Nohup Python Script?

I have a Raspberry Pi connected to a digital temperature probe, which measures my fermenting beer. A python script reads the temperature every second and prints it to the console, and stores it in a ...
4
votes
2answers
394 views

How can I synchronize processes started in different TMUX panes?

Consider this: tmux split-window -d program1 program2 # this program depends on some side effects produced by program1 In this case, program2 will start before program1 is ready. program1 will send ...
4
votes
2answers
1k views

Get line number in a Bourne shell script

I'd like to be able to print the current line number in a shell script. I know about the $LINENO variable in Bash shells, but it doesn't seem to exist in Bourne shells. Is there any other variable ...
4
votes
1answer
188 views

Discard stdout of a command for t seconds

I am working on some batch scripts involving the following: Run some non-terminating sub-processes (asynchronously) Wait for t seconds Perform other task X for some time Terminate subprocesses ...
4
votes
1answer
131 views

Script for “battery level reminder”

I want to plug in the laptop battery charger when the battery level goes down to 40% and then plug it out when the battery charge level reaches 80%. And for that reason, I need a script that would ...
4
votes
2answers
102 views

Using $ in a password

Lets assume that password of my server is Abcd$1234 I am trying to ftp a file from other server to my server using the following in shell script ftp -inv (IP) << EOF user Username Abcd$1234 ...
4
votes
1answer
254 views

returncode of command in a pipline [duplicate]

The following script runs on Solaris using /bin/ksh and on Linux using /bin/sh cmd | tee -a cmd.log | tail exit $? The output of cmd is saved in a file cmd.log and the last lines are displayed on ...
4
votes
1answer
447 views

output while reading keyboard input

I'm trying to write a script that will ssh into a box, start a processes that needs to be monitored (by a human) for success or failure then move onto the next box and repeat. I've been trying to use ...
4
votes
2answers
968 views

Simple Shell script to log disk space

I'm working on automating collecting disk space on a group of servers. In a standard terminal, if I run: ssh server1 ssh server2 df -h Then I get the output of the command, just fine. ...
4
votes
1answer
1k views

Validate AIX Password for root from script

Looking for a way in a shell script to validate the password for for root on an (AIX) matches a standardized plain text password. This query is similar to another one on this site. I have access to ...
4
votes
2answers
343 views

Script for emulating Windows [Win]+[Arrow] keyboard shortcut

I am running Fedora 14. I would like to (at least partially) emulate the behaviour of Windows when you hit Win+Arrow Key. That is, I would like it to "snap" to the left/right sides of the screen. I ...
4
votes
1answer
53 views

Simple problem, Long read: How to overwrite file residing on ESP at Linux boot

First, foundation. Here is my setup: I have a 64-bit dual-boot system running Windows 7 and Linux Mint 17 Cinnamon. I use rEFInd to graphically choose which system to boot. A little bit about ...
4
votes
1answer
216 views

Write the same file multiple times to one file using dd

I am trying to create large dummy files on a drive using dd. I am currently doing this: #!/bin/bash writeFile(){ #$1 - destination directory/filename, $2 - source filepath $3 - blocksize, $4 - ...
4
votes
1answer
241 views

How to write a shell script to run multiple command in different screen sessions?

My goal is to write a zsh script in order to create multiple screen sessions and run separate commands on each of them. I would also like to check at the beginning of my script if there are any ...
4
votes
2answers
560 views

How do I run a script when I switch between keyboard layouts

I use more than one keyboard layout, and I would like to find a way to run a script when I switch between them. Is this possible? So far, I can assign a shortcut for a script like this: #!/bin/bash ...
4
votes
1answer
848 views

Scoping variables in ksh

In ksh, I have two variables with the same name , one global , other one is local to a function #!/bin/ksh LOG_FILE=lf function exec_script { local LOG_FILE=f print $LOG_FILE } exec_script ...
4
votes
0answers
105 views

How to code shell script with command line arguments like -la [duplicate]

Possible Duplicate: How do I handle switches in a shell script? I know how to deal with simple arguments $1-$9 but I don't know how to code it with such as -la, for example ls -la. Could ...
3
votes
5answers
904 views

Lots of elif, is there a better way?

I have a Bash script that looks like #!/bin/bash # FECHA=`date +%j` if [ $FECHA -eq 40 ] then echo "Esta semana le toca preparar el café a Osvaldo" | mail -s 'Café' mailgroup@somedomain.mx ...
3
votes
7answers
3k views

Problem in splitting a string using awk or cut command

I have a properties file which has a password field (key value pair) PASSWORD=NDhhHcsOBofXUdUzGw5B0Q== I am trying to get the value in my shell script using the awk command password=`awk -F "=" ...