The shell is unix's command-line interface. You can type commands in a shell interactively, or write scripts to automate tasks. Use this tag for questions applying to /bin/sh and most compatible shells (ash, bash, ksh, zsh, …).

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3
votes
2answers
102 views

On Ctrl+C, kill the current command but continue executing the script

I have a bash script, wherein I execute a line, sleep for sometime and then tail -f my log file to verify a certain pattern is seen, I press ctrl +c to get out of tail -f and then move to the next ...
2
votes
1answer
51 views

Debian Linux: Start/run application/process in another virtual terminal

You'll have to bare with my my Linux terminology is pretty bad. When I say virtual terminal I'm talking about when you press ctrl+alt+ a function key (F1-F12). I think they are called virtual ...
0
votes
2answers
9 views

Manually executing a CRON - Confused about params

I have this code snippet: $CUSER=tim $APPDIR=/var/www/testing $APPVENV=/var/www/testing/ven cat > $APPDIR/cronfile << EOF PWD=$APPDIR/$CUSER PATH=$APPVENV/bin:\$PATH 0 2 * * * testapp search ...
0
votes
1answer
50 views

Command “>” failing in Embedded Linux only

I'm developing an app in Qt for Embedded Linux where I want to see how much (%) of the given partition is occupied. I found on the web that a way to do this would be by calling the df command passing ...
1
vote
3answers
145 views

The equivalent of cmd “for” in bash?

I'm a Linux newbie, and I only know little about bash (or any Linux shell - but I just use bash). I'm used to using for %c in (*.*) do {something} in cmd in Windows, and I really feel inconvenient ...
0
votes
2answers
44 views

How to use variables properly in this little script?

Here is a little script to retarget old-wrong symlinks that I want to make interactive. #!/bin/bash # retarget (broken) symbolink links interactively echo -n "Enter the source directory where ...
0
votes
2answers
42 views

How to add a column if line contains string?

If I have a tab-delimited file containing the following lines: Sample1-Baboon 1 2 3 4 Sample2-Human 1 2 3 4 Sample3-Human 1 2 3 4 Sample4-Baboon 1 2 3 4 How can I add a new column ...
2
votes
1answer
48 views

Equivalent of “which” in sh [duplicate]

I found out today while developing a shell script that which is not a builtin for sh. What is a good equivalent?
1
vote
1answer
43 views

Display result of a command right aligned in terminal

I have a script that goes through many different checks and I use the success, failure functions defined in /etc/init.d/functions to clearly show the action result on the terminal. That works great, ...
1
vote
0answers
31 views

Autocomplete issue in bash with equal sign (=)

I am trying to make autocomplete work and wroted a piece of code to demonstrate an issue I faced up: $ cat completion.sh function _completion_command() { compopt +o bashdefault +o default +o ...
52
votes
4answers
3k views

Why is `[` a shell builtin and `[[` a shell keyword?

As far as I know, [[ is an enhanced version of [, but I am confused when I see [[ as a keyword and [ being shown as a builtin. [root@server ~]# type [ [ is a shell builtin [root@server ~]# type [[ [[ ...
1
vote
4answers
52 views

Dynamically reference a file's name

In a single directory, I'd like to replace the first line of each file with the file's name. Each file has as the first line "TestRelation." I'd like to replace it with the file's name. I know I can ...
1
vote
3answers
90 views

How to pass an array to a function as an actual parameter rather than a global variable

Is there a way to pass an array to a function as one of its parameters? Currently I have #!/bin/bash highest_3 () { number_under_test=(${array[@]}) max_of_3=0 for ((i = 0; ...
1
vote
1answer
31 views

Can .bash_profile be auto sourced after change?

I'm always wondering if there's a way to do this. I don't want to type source after changing my .bash_profile all the time.
0
votes
0answers
22 views

what is the meaning of “${x%*.*}” in shell? [duplicate]

While I am using the code as ${x%*.*} it is excluding the extension of the file. for e.g. $ x="file.txt" $ y="file.20150208.dat" $ echo "${x%\*.\*} ${y%\*.\*}" file file.20150208 But how this ...
0
votes
1answer
19 views

What is the meaning of “${name##*/}” in Shell [duplicate]

I have a code as while read name; do uuencode "$name" "${name##*/}"; done but I do not understand what is meaning of ##*/ in "${name##*/}" Google doesn't give good results. Can someone please ...
1
vote
2answers
139 views

Perform multiple commands on one line

There are two steps, that I would like to be run on one line: twinkle -c then call sip:in06khattab@sip.linphone.org Here is the output: I wanted to perform these two steps on one line, I ...
3
votes
3answers
139 views

How to rsync files between two remotes?

I would like to transfer files between two remote hosts using on local shell, but it seems rsync doesn't support synchronisation if two remotes are specified as follow: $ rsync -vuar host1:/var/www ...
0
votes
2answers
67 views

In a shell script, How to give a variable another value after one job is done?

I'm trying to make a script which will see if the directory exists and will zip all of its contents under it according to the name/path of the directory. The farthest I could go was - ...
0
votes
2answers
63 views

Help to read a flat file into unix and output to simplified csv like format for import into excel

I have a text file that has data written to it in the format below, its thousands of rows. The new record always begins with WHATEVER.RDNDISPLAY or WHATEVER.DSPLY_NAME. The name of the record is ...
4
votes
3answers
83 views

Bash, insert last used argument of current command

I'm aware that you can recall the last argument of the previous command with !$ and also cycle through previous arguments with ALT + . but can you recall the last argument used for the current command ...
0
votes
5answers
61 views

sed to replace with backspace

I have trail.txt, which contains spice netlist. Now I want to replace all expanded parameters to one line only i.e. remove + and append that line to previous line. trail.txt data + net06706 ...
0
votes
4answers
33 views

adding programs to path [duplicate]

I have a load of tools that are kept in the /opt directory. The tools are organised like this: /opt/toolname/tool.sh. My question is, how can I add the tools in my /opt folder to my path, so i can run ...
3
votes
2answers
57 views

Loop over files returned from find?

I'm trying to piece together a script that recursively finds all the *.plist files in a directory and then operates on them. The script is below, but its producing unexpected results. The expected ...
0
votes
1answer
28 views

Running a “scheduled”/delayed script as sudo on server, via ssh - and right before ssh exit

This would have probably been answered by Keep running a script via ssh, if I didn't have to run a command as superuser. Let me try with an example: say on my server, I have this script as ...
1
vote
3answers
56 views

Shell script to find and count total number of characters in all the files

How can I make a script that finds every file in your home directory that is less than 3 days old and then gets a count of the total number of characters in all of these files?
0
votes
1answer
30 views

Error while executing a.out from C shell

I am in my home directory. And there is an executable a.out in there. I want to execute it like- /bin/csh ~/a.out ^F^E@@@@@▒^A▒^A^H^C^D^B^B@^B@^\^\^A^A^E@@: Event not found. Its not that I cannot ...
1
vote
1answer
100 views

Set up graphic interface (desktop) for remote connection

I was assigned a CentOS VM that I manipulate through Putty. Everything I do to it is by command line so far, and I have admin rights to it. The VM is stored in the corporate data center served up by ...
0
votes
2answers
66 views

Use .sh or .bash extension for bash scripts?

(See Use #!/bin/sh or #!/bin/bash for Ubuntu-OSX compatibility and ease of use & POSIX) If I want my scripts to use the bash shell, does using the .bash extension actually invoke bash or does it ...
9
votes
4answers
487 views

Use #!/bin/sh or #!/bin/bash for Ubuntu-OSX compatibility and ease of use & POSIX

I know that I can use either as the first line of scripts to invoke the desired shell. Would #!/bin/sh be recommended if compatibility with all unix systems is an absolute requirement? In my case ...
0
votes
1answer
23 views

Can I treat all what I typed after a command as raw string?

I made a bash func for myself so I can through some words into a tree_hole file, it looks like this in bashrc: function th { echo -e "\n$@" >> /Users/zen1/zen/pythonstudy/tree_hole; } export -f ...
1
vote
4answers
51 views

Create copies of files in same directory

Lets say I have a directory with the following files: 1.txt 2.txt 3.txt I want to copy these and basically paste in the same directory making new files eg: 1.txt 1(1).txt 2.txt 2(1).txt 3.txt ...
0
votes
1answer
62 views

How to know, when a shell command running in the backround getting killed or died

I am running a shell command which is invoking an avconv session. The command is running as a background process. When the script starts executing I am doing a curl post to a url with the created ...
7
votes
2answers
263 views

How do redirection in a symbols work in a sequence?

I have file1, file2, file3. file1 contains 1 file2 contains 2 file3 contains 3 I use command cat file1 > file2 > file3 Results in: file1 1 file2 (contains nothing) file3 1 Why ...
0
votes
2answers
33 views

Integer input constraints

I want to make an input constraint on read: Terminal Shell; read x read y echo $(($x+$y)) I want to make a constraint of x, I want x to be -100 <= x <= 100. What's the command I insert ...
1
vote
3answers
67 views

Cronjob doesn't execute shell script, but when I am executing it standalone it works. Why?

Shell Type: >echo $SHELL /bin/ksh Cronjob : 15 * * * * /bin/ksh /wls_domains/resMGT/logs/bea/wlr3queuetransaction.sh > /wls_domains/resMGT/logs/bea/data/script.log The script is as below: ...
1
vote
1answer
62 views

Running init script which starts a deamon in background for reducing boot time?

I'm looking for ways to speed up the boot time on a single core embedded Linux system. Significant lag happens during start up of some custom daemons. Once they are up, they do run in the background, ...
4
votes
3answers
120 views

How to use GNU parallel effectively

Suppose I want to find all the matches in compressed text file: $ gzcat file.txt.gz | pv --rate -i 5 | grep some-pattern pv --rate used here for measuring pipe throughput. On my machine it's about ...
1
vote
0answers
35 views

Cannot change bash shell in Mac OS X

I'm trying to update bash shell on my Mac OS Mavericks. $ brew install bash $ which -a bash /bin/bash /usr/local/bin/bash $ which bash /bin/bash $ chsh -s /usr/local/bin/bash $ which bash /bin/bash ...
1
vote
2answers
61 views

How to extract a part of file name in unix/linux shell script

My file name is Oracle.2347263_testing_152607.csv I tried this : echo Oracle.2347263_testing_152607.csv | sed -e 's/.*G.//' \-e 's/.csv//' but I didn't get the result I expected. I want to ...
3
votes
1answer
77 views

Triple dot wildcards

I have a very large directory structure of source code that is very difficult to work with. I would like to run a tool to transform it to a Maven like structure that works better for me. When I have ...
13
votes
4answers
1k views

Write Python stdout to file immediately

When trying to write the stdout from a Python script to a text file (python script.py > log), the text file is created when the command is started, but the actual content isn't written until the ...
0
votes
1answer
79 views

“too many arguments in [ (test) statement”

this is my first "if-else" script on linux. It gives the error [: too many arguments Code: n=0 if [ $n % 2 -eq 0 ] then echo "even number" fi How to correct it.
2
votes
1answer
46 views

Multi-month view in calendar (cal) in OS X

I am hoping to run some of the commands listed in this article, e.g.: cal -3 which is supposed to show me the last month, this month, and next month. This command does not work in OS X. $ cal -3 ...
5
votes
4answers
266 views

How to move all files inside present subfolders up here

I have 50 folders with some subfolders too, with more than 1000 audio files total. I need to remove all subfolders and put all files in present level. Tried mv */* ./ but it complaints: argument list ...
15
votes
5answers
2k views

Generating a random password; why isn't this portable?

I want to generate a random password, and am doing it like so: </dev/urandom tr -dc [:print:] | head -c 64 On my laptop, which runs Ubuntu, this produces only printable characters, as intended. ...
4
votes
1answer
69 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 ...
1
vote
1answer
33 views

Calling bash getopts from a function fails the 2nd time

I'm trying to parse arguments passed to a bash function using getopts inside that function. It works when the function is called for the first time but fails on all subsequent calls. Here is a simple ...
20
votes
2answers
1k views

Pipes, how do data flow in a pipeline?

I don't understand how the data flows in the pipeline and hope someone could clarify what is going on there. I thought a pipeline of commands processes files (text, arrays of strings) in line by line ...
2
votes
1answer
36 views

Intercept and modify commands in bash scripts

I have some scripts and some commands in the scripts are like this ./executable arg1 arg2 .. argn I want to change the above command to LD_PRELOAD=/some/lib ./executable my_arg1 my_argn arg1 arg2 ...