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

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4
votes
2answers
662 views

Script to loop through folders with numeric names

I am working on a bash script to compress the images in my Wordpress folders. The wordpress folder structure is as follows: > wp-content/uploads/2014/01/filename.jpg > ...
2
votes
2answers
195 views

printf output running over into next line

I have created Bash SS in vi. My output is running over into the line below it. I am new to UNIX so I'm trying to learn. My output is displayed using printf. printf "%-15s %15s %15s %2d\n %2s " ...
14
votes
3answers
8k views

Variable as command; eval vs bash -c

I was reading a bash script someone made and I noticed that the author doesn't use eval to evaluate a variable as a command The author used bash -c "$1" instead of eval "$1" I assume using eval ...
0
votes
1answer
91 views

How to assign variable in awk

I have a code like below: $ awk -F'[]]|[[]' \ '$0 ~ /^\[/ && $2 >= "2014-04-07 23:00" { p=1 } $0 ~ /^\[/ && $2 >= "2014-04-08 02:00:01" { p=0 } ...
5
votes
2answers
327 views

Get the actions for a command programmatically

Let's take the git example: $ git<TAB><TAB> git git-import-dscs git-shell git-buildpackage git-import-orig git-upload-archive git-dch git-pbuilder ...
2
votes
1answer
66 views

Conditionals for fish shell

I am going through the fish shell tutorial and find that this simple if-else block does not work if grep fish /etc/shells echo Found fish else if grep bash /etc/shells echo ...
2
votes
1answer
1k views

How to check input parameter for running shell script [closed]

I'm writing a shell script to be used for various purposes. Various operations depend on input parameters. How can I check which parameter has been passed to the shell script while it runs? Can ...
0
votes
3answers
5k views

How to write a Java Program / Shell Script combination such that you can call the Java program as a remote command and yet supply a local file?

This is related to How to execute a remote command on a local file? I wrote a simple Java program that prints the first line of a file - import java.io.BufferedReader; import ...
6
votes
4answers
4k views

How to extract logs between two time stamps

I want to extract all logs between two timestamps. Some lines may not have the timestamp, but I want those lines also. In short, I want every line that falls under two time stamps. My log structure ...
2
votes
1answer
97 views

Multiplex bash function execution

I created a bash function to "automagically" connect on our switches and retrive their startup-config using the expect command. I have to use expect because this switch does not accept the ssh ...
1
vote
1answer
68 views

Shell script fails to run on startup

I want an executable program to run on startup. For this reason, I created a shell script: /etc/init.d/server. Then I run chmod +x name_of_script and update-rc.d server defaults. server (script): ...
1
vote
0answers
69 views

Execute commands on TMUX Detach

Is it possible to execute commands on tmux detach? I usually have a rails console and server running in the tmux session, on detach is it possible to automatically end those? Thanks.
1
vote
1answer
95 views

extracting specific substrings from string

I am trying to write a bash script. In a directory I have 2 fastq files: A-122-3.BH7WBVADXX.lane_1_P1_I24.hg19.sequence.fastq A-122-3.BH7WBVADXX.lane_1_P2_I24.hg19.sequence.fastq I just want to ...
1
vote
2answers
424 views

shell script to find the combination of the array elements

I have a shell script in which I have defined an array. The array contains more than 2 elements. I need to find the combination of all the elements in my array. Suppose, if my array has the elements, ...
1
vote
2answers
3k views

copy files from one path to another path in linux

I am new to linux. I am trying to copy files from one path to another path. I have a text file which has all names of files in the following pattern: file-1.txt file-2.pdf file-3.ppt .... I created ...
1
vote
2answers
2k views

Editing a Java properties file with Bash

I have the following Java properties file that is maintained by humans. # file.input = /very/old/name # file.input = /old/name file.input = /current/name file.input.default = /default/name ...
0
votes
0answers
35 views

How to find the currently running app from terminal on OS X?

I'm writing a shell script runs in the background and monitors user activity. I'd like to be able to capture current application/document if possible. Can I do that? (Cross-posting this from ...
1
vote
2answers
65 views

command condition sometimes integer sometimes string

I want to execute this condition while [ $(cat /path_of a file/) -eq 1 ] The condition is only correct if $(cat /path_of a file/) is an integer and not a string ! How can I overcome this ...
3
votes
1answer
7k views

Bash command not found error

Why would the following script give following errors : ./check1.sh: line 10: Hi,: command not found ./check1.sh: line 21: syntax error: unexpected end of file check1.sh: #!/bin/bash subj="host ...
0
votes
1answer
137 views

Recursively delete hidden directory & its files?

I want to delete all hidden directoris from a directory and its sub-directory. I also use rm -rf .directory_name this command is iterative command I want to a recursive command. Please anybody help ...
1
vote
2answers
668 views

Bash: split list of files into different files?

I have several files in a directory like: data1.dat data2.dat .... data24678.dat To run another code, I need to have a text file with the names of the files but I need to split in 50 files per ...
-2
votes
2answers
63 views

How to delete a directory from terminal?

I'm trying to delete a directory after a series of events take place. That being said, I need to be able to place this in a file to execute once said events take place.
4
votes
3answers
287 views

How do I read the output of commands in a script

I'm learning Linux scripting at the moment, and one thing I can get working is assigning a command output to a variable. The command service httpd configtest returns Syntax is OK, so I wrote this. ...
8
votes
2answers
224 views

How do I elevate privileges in the middle of pipeline?

My guess was as follows: echo "Generating some text" | su - -c cat >/output/file But su says: su: must be run from a terminal What would you do?
0
votes
1answer
120 views

Can continually assigning a variable in a shell script cause a memory leak?

I've written a short script to copy Apache's server status to a log: #Save date and time to a variable dt=$(date) #Echo date and time to the log file as it's not included in server-status echo "Time ...
1
vote
0answers
69 views

Running a script after tty1 has loaded

I have been attempting to write a script to run dcled on start up, the program that runs this. I am using Debian Jessie with multiarch enabled. This is essentially a small file server. I am ...
4
votes
2answers
689 views

How to kill a process started as daemon?

I start a process using foo &. It outputs something like: [1] 16915 This is the process id, I guess. How can I store this number into a variable named MY_PROCESS_ID (for example)? Then I ...
10
votes
4answers
4k views

Using “${a:-b}” for variable assignment in scripts

I have been looking at a few scripts other people wrote (specifically Red Hat) and a lot of their variables are assigned using the following notation VARIABLE1="${VARIABLE1:-some_val}" or some expand ...
1
vote
1answer
80 views

mailx and HP-UX to RedHat migration

We are migrating some servers from HP-UX to Linux RedHat, and we have to migrate about 100 shell scripts that are referencing /usr/bin/mailx (instead of /bin/mailx on Linux). We'd like to change all ...
0
votes
2answers
170 views

Scripting Language Evolution [closed]

I have an assignment due Monday and I need some help because I have no knowledge on the subject and can't even understand what to search exactly. I am not waiting for an essay or something just some ...
10
votes
1answer
4k views

How can I tell whether a package is installed via yum in a bash script?

I am trying to write a script that installs packages, but if it fails at any point later in the script rolls back whatever it installed. Of course if the user has already previously installed a ...
9
votes
6answers
926 views

A bash function that takes argument like other languages?

I have a bash function to set the $PATH like this -- assign-path() { str=$1 # if the $PATH is empty, assign it directly. if [ -z $PATH ]; then PATH=$str; # if the $PATH does ...
0
votes
2answers
728 views

Bash split a list of files

I have 200 files in a folder like: test_1_cfg.dat, test_2_cfg.dat,.... and so on. I need to include in a bash script the first 40 files as input and run some process, another script to read the next ...
0
votes
1answer
279 views

How to pass a flag from one script to a function in another script

I have a script that installs a bunch of programs (homebrew, git, etc) and I have it log to stdout all the things that its doing along the way, but I want the ability to pass a flag, such as --no-log ...
4
votes
3answers
2k views

Bash, how to let some background processes run but wait for others?

I have (yet) another wait, &, && control flow question.. Say I have a script something like this where I want to do as much work at the same time as possible: # may take some hours ...
0
votes
1answer
48 views

Script in C shell skipping over last else statement?

This is a C shell script that checks the number of arguments and if the file/directory exists. When the arguments are valid, it should go to the last else statement and print "hi", but when I run this ...
-1
votes
2answers
104 views

Add users from dat file

I have a dat file with names. These are the names of users I must add, without groups or passwords. Ofcourse i have to remove all spaces. I have to add them with a bash script. Can anyone help me ...
3
votes
2answers
655 views

Unable to launch the requested CGI program: /www/cgi-bin/first.cgi: Text file busy

I'm trying to make a very simple shell script to run as a CGI on a uhttpd server running on an OpenWRT install. The file is called /www/cgi-bin/first.cgi and looks like... #!/bin/sh echo ...
0
votes
1answer
68 views

Scripting - Folders with spaces

I'm trying to write a script that's robust enough to work with spaces. Its currently in a for loop, but the problem I'm having is folders with spaces in its name. ASOURCE="Home Photos 2012 ...
8
votes
3answers
10k views

What does $# mean in shell?

What does $# mean in shell? I have code such as if [ $# -eq 0 ] then I want to understand what $# means, but Google search is very bad for searching these kinds of things.
1
vote
1answer
1k views

Divide a variable by a number? [duplicate]

Basically I need to convert centimetres to inches which I am trying to do by diving the area in centimetres by 2.54. But I just cannot get this to work. echo "please enter width and then height" ...
4
votes
2answers
158 views

Spliting `File` and `directory name with space' via shell script

I've got a file called Files.txt having following content: TestApp/Resources/Supporting Files/main.m TestApp/Resources/Supporting Files/AppDelegate.h TestApp/Resources/Supporting Files/AppDelegate.m ...
7
votes
4answers
2k views

How to run parallel processes and combine outputs when both finished

I have a bash shell script in which I pipe some data through about 5 or 6 different programs then the final results into a tab delimited file. I then do the same again for a separate similar dataset ...
0
votes
1answer
631 views

Where are RPM postinstall scripts located?

I have found a bug in an RPM that I have been provided. rpm -qp --scripts foo.rpm > /tmp/badscript cat /tmp/badscript postinstall scriptlet (using /bin/sh): ... if [ 'some bug' == true ].... I ...
0
votes
2answers
202 views

bash function output to pipe [closed]

I made a bash function to beautify svn output, this function show logs one line per commit, it is great! I like it, but if I use it with pipe it does not work. You can find it on github svn-beautify ...
3
votes
2answers
4k views

Range of the command cut in unix

I'm trying to make a shell script, I want to cut a string using the 'cut' unix command, as follows: namecmpaux=$(echo $namecmp |cut -c0-19) But when I run the shell tells me the following error: ...
2
votes
2answers
162 views

Shell Scripting: how to use part of the file path as the file name?

I have a group of directories, each containing exactly 1 jpeg image, like so- /psds/folder1/image.jpg /psds/someotherfolder/picture.jpg /psds/yetanotherfolder/thumbnail.jpg What is the appropriate ...
1
vote
1answer
309 views

Date calculation in script for notification alerts

I want to create account expiry alerts therefore I need to write a script which could alert me before 1 month of expiry over email. I'm working on Linux. I can get expiry information as 2015-27-03. ...
1
vote
1answer
852 views

Run smartctl on all disks of a server

My question is a quite simple , I want to run the command smartctl -i -A on all disks that the server have. Think that I've too much server with different number of disks and RAID Controllers, then I ...
2
votes
1answer
142 views

Turning off default video output with xrandr when external monitor is connected

I'm new to bash scripting, and I'm trying to configure my video outputs so that my laptop display gets turned off when I connect an external monitor via VGA. That's the script I came up with, pretty ...