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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11
votes
2answers
764 views

What's the best distro/shell-agnostic way to set environment variables?

The question says it all. I currently use Arch Linux and the zsh, but I'd like a solution that (at minimum) works both on VTs and in xterms and also (hopefully, preferably) will continue to work if I ...
4
votes
5answers
348 views

Only output most recent 10 (or n) lines of a lengthy command output

I have currently worked alot with shell and bash on linux. I have made tons of backups scripts and much more. In many cases I have a command that outputs thousands of lines. I actually need these ...
8
votes
2answers
10k views

Why doesn't my ~/.bash_profile work?

I'm using Linux Mint. My login shell (cat /etc/passwd | grep myUserName) is bash. After I start my graphical desktop environment and run terminal emulator from it, I could see that .bash_profile is ...
2
votes
2answers
110 views

Filtering the result of the find command, so that it returns only directories

Is it possible to get only the results from find that are directory paths? Using find with some option, or using grep or some other utility the results are piped into as a filter? I thought something ...
2
votes
2answers
283 views

Writing scripts that use different commands in different shells [duplicate]

How can I write a script that is shell independent? I want to be able to run one script which will run in ksh, sh and bash. For example: If I have a line in my script like whence ls which will run in ...
3
votes
2answers
496 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 ...
2
votes
3answers
198 views

Simplified navigation in terminal

I know IDEs are the wave of the future, but I always find myself coding in vim in a Linux terminal. Old dog. New tricks. Anyway, navigation becomes challenging when dealing with long package names. ...
7
votes
2answers
2k views

What does “cd &” mean?

I know how to change directory from terminal by typing cd <directory> but here's the scenario. I was using terminal to go on my git repository's folder. glennRepositories ...
2
votes
2answers
3k views

Shell Script - syntax error near unexpected token `else'

With the following shell script, why I am getting errors syntax error near unexpected token `else' Shell Script echo "please enter username" read user_name echo "please enter password" read -s ...
1
vote
1answer
395 views

Error not a valid identifierd when executing shell script [duplicate]

I have the following shell script in order to connect to database and do some tasks. echo Please enter userid: read USER_NAME echo "Please enter password:" read -s PASS SID=${ORACLE_SID} if [ ...
1
vote
0answers
57 views

Where does backtick and single quote come from when denoting commands e.g. `prog'? [duplicate]

When referring to commands in tutorials, man pages, and articles I see authors use the backtick and single quote in this way: `./configure' `make' I believe I have seen gcc denote points of failure ...
0
votes
1answer
287 views

Cat into fifo not running through bash

I want to script these few lines mkfifo my.fifo cat >my.fifo & cat my.fifo | nc remotehost.tld 10000 But the line cat >my.fifo & When i run it manually it works, but not through ...
1
vote
2answers
1k views

Find and move directories based on file type and date

I have a directory "New Movies" containing 200+ subdirectories "Movie Name (year)". The subdirectories "Movie Name (year)" contains a single video file (avi/mkv) and several related jpg/xml files. I ...
2
votes
2answers
259 views

Bashrc disable-ing all but a given command for a given user

Is it possible to have bashrc grab every single command the user types, save for those containing a given word? Like the way you can use aliases to change what the user meant, you can alias for ...
16
votes
2answers
2k views

Is there an easy way to programmatically extract IP address?

Is there an easy way to programmatically extract IP address, without tedious parsing of ifconfig? I would not mind simple command output processing using sed to do it but not processing multiline ...
2
votes
3answers
367 views

Unexpected condition outcome in a ksh script

I'm new to shell scripting. The below code is not working. Can anyone help me on this? I've given explanation for all the lines: #!/bin/ksh cat example.txt | while read LINE # ...
12
votes
1answer
11k views

How can I execute local script on remote machine and include arguments?

I have written a script that runs fine when executed locally: ./sysMole -time Aug 18 18 The arguments "-time", "Aug", "18", and "18" are successfully passed on to the script. Now, this script is ...
2
votes
4answers
759 views

Can awk use field identifiers also for shell strings (variables)?

Well, this apparently is not possible the way I'm trying it. This alternate approach to obtain bar as a resulting string works, though: #!/bin/bash path1=/usr/tmp/foo/bar/baz awk -F/ '{print $5}' ...
4
votes
4answers
1k views

Why cat, grep and other commands can't understand files starting with minus sign? [duplicate]

If I have a file which name starting with single or several minus sign, for example --1 it can't be used as a parameter of many commands. Even if I run cat --1 instead of file content I get ...
0
votes
1answer
95 views

Converting a loop of code to function

I want to retry a command for 5 times with an interval of 20 seconds. I want this command to be passed as a method parameter. How to do it? And once the function is written how to pass the value to ...
1
vote
2answers
1k views

Busy box Read file line by line

There is no read applet comming with busy box. Is there any way to read a txt file line by line using busybox? What I have now is while read line do echo $line done < "$InputFile"
3
votes
2answers
1k views

Optimizing a shell script with long running while loop

I have written a shell script which has to do the following: Capture session commands into one file. Every individual command into separate file. Mail every individual command file content based on ...
1
vote
3answers
597 views

Escaping * with Regular Expressions and Grep

I have a file that has unique lines that start with 2 stars (**). However when I run a grep command for grep \*\* fileName I get all of the lines in the file. This is very unusual, and what I ...
2
votes
2answers
110 views

Absolute path to currently-running zsh?

Sometimes the output of ps -p $$ shows the absolute path to the currently-running zsh, % ps -p $$ PID TTY TIME CMD 1027 ttys005 0:00.11 /usr/local/bin/zsh but not always: % ps -p ...
1
vote
2answers
383 views

Booting into shell instead of graphical interface [duplicate]

I have a laptop with lubuntu. It's great but I wish LXDE was optional instead of autostarting. So my question is, what can I do to make it boot directly into a text only mode, not loading anything ...
1
vote
4answers
161 views

All subprocesses are Bash (!),

I was trying to use GDB, and found that whenever it attempted to spawn the program I was debugging, Bash was spawned instead (GDB would say starting myProg..., and then Bash would appear. When I ...
3
votes
1answer
769 views

find and rysnc?

I want to be able to search for files over 14 days and over 10k and than rsync those found files to a destination. Is there a way to combine these two commands? find ./ -mtime +14 -size +10k rsync ...
3
votes
1answer
123 views

watch command to delete files in a directory every N secs

I thought of using watch command to delete files in a directory every N seconds with the command running in background. This is what I was planning to use: nohup watch -n1200 rm -rf ...
14
votes
2answers
553 views

Why does `exit &` not work?

I don't understand why exit & does not work. Why does it not?
4
votes
1answer
331 views

Send stdin to console and compressed file

I'm running a propietary program which generates text output. Kind of like a logger. logger I'd like to both view this output on the terminal to watch the server breathe, and send it to a text ...
2
votes
1answer
392 views

Why doesn't terminal show color schema once logged as root?

I'm currently using Debian 7 Wheezy, and I've noticed that the colors palette on terminal (which might be useful to identify among a large set of files and folders) are not enabled once I log as root. ...
3
votes
3answers
562 views

Quote a variable in shell script “if” statement

e.g. if [ "$FOO" = "true" ]; then vs if [ $FOO = "true" ]; then What is the different? Seems both of two statements also works.
1
vote
1answer
2k views

i/o format with printf in bash-shell

I am trying to output the results of my shell script using printf. To keep the results aligned in column, I am using tab as: printf "%s\t %s\t %s\t %s\t %s\t %s\t %s\n" $i $est $var_m $jk $mst $var_M ...
1
vote
1answer
175 views

How to give variable to a KSH script with a CGI?

index.sh is in the cgi-bin directory: #!/usr/bin/ksh echo 'Content-type: text/html <html><body> <form action=FOO.KSH method=POST> <input type=submit value=fgrep ...
1
vote
1answer
91 views

Numbering the output of grep

When we're filtering the output with grep, is there any way we can get line numbered output, like we get with cat -n? I'm not asking for the grep -n option which shows the line number of the match in ...
0
votes
1answer
197 views

Stream grep from subprogram, not tail file

Does a simple one liner exist for grepping continuous output from a program rather than just a file? Now just as an example, I would like to skip lines containing PHPUnit in them. For obvious reasons ...
2
votes
2answers
345 views

See extended attributes with coreutils ls on Mac

I have coreutils installed via MacPorts on my Mac running OS X 10.8.4. I have ls set to use the coreutils version of ls [(GNU coreutils) 8.21] when available: if [ -e /opt/local/libexec/gnubin ]; ...
1
vote
1answer
46 views

How to customize a backend running job completion message?

Here is the situation, I am running a command (my own executives), in bash shell (Ubuntu), say something like this: [newbie@office currentCaseAFolder]$ FEMSolver & So that the FEMSolver job is ...
6
votes
4answers
8k views

What does ampersand mean at the end of a shell script line?

sh sys-snap.sh & What is sh? What is sys-snap.sh? Why I should put & at the end of the line? Can anyone explain the syntax? Without the & the script won't go back to the prompt till I ...
5
votes
5answers
3k views

How to append data of multiple files into single file?

For example: I have 01.txt and 02.txt files and need to append data of these files into new file new.txt. It should append data based on 01.txt followed by 02.txt files. Before this I have to delete ...
0
votes
2answers
977 views

Why does `at` warn me that commands will be executed using /bin/sh? What if I want a different shell?

I tried to use at from within a script of mine and it prints: warning: commands will be executed using /bin/sh How would I use different shell if I wanted?
6
votes
4answers
2k views

Bash script to rename files from a text file source

I'm fairly new to bash; I can just about perform simple administrative tasks with simple commands 1 at a time. However, I've been tasked with renaming some files in a directory using a text file as ...
9
votes
2answers
2k views

How can you log every command typed

How can you log every command someone has entered into the shell? I'm asking on both the basis of protecting yourself if you are logged into someone else's server and something breaks, or if someone ...
1
vote
3answers
138 views

Taking Backup of files of particular limit in unix

Here is the scenario, I have 1000 files in a folder each ~3 MB. I want to zip all files into 50MB each zip and remove the original files. NOTE: 50MB may contain 20 files or 10 files but that zip ...
3
votes
4answers
244 views

Show video files with its size

I need all the .mp4 files' dimensions to be printed with the file name. For example: 1_VIDEO.mp4 1204x680
1
vote
1answer
43 views

Cannot figure out how to revert back to backed up profile file

Basically, I made a backup copy of my /etc/profile (or ~/.profile I can't remember exactly) file that executes as soon as you login to a TTY, and then I changed the one that was there, and now it ...
2
votes
3answers
5k views

Why do I get error “Could not chdir to home directory”

I work in support, and occasionally I'm given shell access to a remote Linux system. I frequently find that when the admin gives me remote access, that I get the following output upon login. ...
1
vote
1answer
154 views

Why does export not seems to affect child shells?

if I have $ x='This is a String' $ export x $ xterm & [3] 14089 The child process doesn't seem to respond to $echo $x $ Update: The FIRST time I export the variable it seems to span a ...
1
vote
2answers
693 views

How to terminate a hung process in SSH?

I have a SSH session with a VM running on Amazon AWS. One of the programs I had run hung up and froze the SSH terminal. So I hit Enter+~+. Now when I am trying to connect to my machine it says ...
4
votes
5answers
2k views

grep for multiple strings in files, and then list the files in the order of size

I am in a folder with lots of .txt file, I would like to find all the files which contain both stringA and stringB (not necessarily on the same line), then list these files in the order of the size ...