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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1answer
33 views

How to assign words with spaces as a whole name to variable in shell script? [duplicate]

I need to make some directory of Author name. It's easy when doing them alone. I can simply mkdir "Mario Luis Garcia" This will create one directory named "Mario Luis Garcia" But when trying do it ...
4
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1answer
202 views

command: ls /etc | sort | grep d* is yielding no results but ls /etc | sort | grep p* lists entire directory

I am playing around with piping and grep tonight. I know that grep uses regex and that * means 0 or more occurrences of the preceding character. So the way I understand it is that if I do the ...
8
votes
4answers
1k views

Why is the 'if [ $1=“1” ]' branch always selected even if $1 is not 1?

I have a shell script named 'teleport.sh' like this: if [ $1="1" ]; then shift mv "$@" ~/lab/Sun elif [ $1="2" ]; then shift mv "$@" ~/lab/Moon elif [ $1="3" ]; ...
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1answer
30 views

Can you further integrate and present sequential moreutils vipe command output in vim using successive splits etc?

I have used the moreutils suite a few times and I find it makes you think further about base utilities and is insightful(and fun). For instance, vipe allows running an editor - like vim - in the ...
0
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2answers
76 views

Getting expr: syntax error on index [duplicate]

Using this OF=$(ps fax | grep 'php-fpm: master process' | awk '{print $1}') IDX=`expr index $OF ' '` I get an error. The results of the $OF variable are: 27797 27495 What is the error here? I ...
3
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1answer
33 views

Can I make “less” execute arbitrary commands with a single key sequence?

The crux of my question is stated in the title. Reading the less and lesskeys manpages, I have created a file containing: ^B shell touch ~/testfile and run it through lesskey to generate ...
11
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3answers
594 views

How to undo `set -x`?

I typed set -x in terminal. Now the terminal keeps printing the last command run on top of my output so the command ~]$echo "this is what I see" returns + echo 'this is what I see' this is what ...
2
votes
1answer
67 views

Why does `cp -a . /dir` copy contents instead of directory?

I wanted to copy a directory that I was presently in. I tried cp -a . ~/xyz It copied the contents of the directory, yet this worked: cp -a "$(pwd)" ~/xyz [As desired, this copied the directory ...
1
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3answers
103 views

Why is ls command slow to interrupt on NFS directory with lots of files?

I noticed in directories with lots of files on NFS if I do ls * then hit Ctrl-C it can take a while ( say 20 seconds ) before ls comes back. Why? Can ls command be fixed to be more responsive?
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2answers
27 views

moving a process to fg and bg [duplicate]

Suppose I run a process in the background likw ./script &, I can bring it to foreground by running fg. However, is there a way to move it back to background without stopping it (as in ctrl+z) or ...
1
vote
3answers
88 views

How to get a response from any URL?

I have been asked to write a shell script To check if a URL is UP/Working or not for my Project. I tried to find some hints over the internet, but whatever I got is about checking whether the URL ...
3
votes
5answers
253 views

How to use a shell variable inside sed's s command? [duplicate]

we know that we can get the value of a variable using $ sign: x=3 echo $x 3 Is there other ways that we can use to get the value without using $ sign. I'm asking this because $ sign is a special ...
2
votes
5answers
45 views

Append files with bash one-liner?

Currently I use multiple lines to append content into a combined file, e.g. ./myprogram 1.txt > Out.txt # Overwrite for the 1st file ./myprogram 2.txt >> Out.txt ./myprogram 3.txt >> ...
1
vote
1answer
88 views

Canot remove symlinks: after reboot, symlinks re-appear

Using ssh from BusyBox, I cannot remove symlinks: after rebooting the device, symlinks re-appear. ls -la shows that symlinks have been removed, but after rebooting device they re-appear again. Those ...
3
votes
1answer
45 views

Escape closing parentheses from URL with firefox -remote

I have this command (for detailed info see Shortcut to google selected text): sh -c 'firefox -remote "openURL(http://www.google.com/search?q=$(xsel),new-tab)"' But when I select a text which ends ...
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votes
1answer
42 views

to run script over several folders? [duplicate]

Currently I have a script that can run only in a single folder. #!/bin/bash for file in ls -1 *.jpg|sort -t . -n -k 3 do echo "compute ./scripName $file" ./scriptName $file done Question: I ...
0
votes
2answers
42 views

Determining the exit status of the “return” built-in

I was reading about traps, but only return works for me in my shell script, so was wondering what status or code it returns, so what I tried is, #!/bin/bash seeOutput=`return` echo $seeOutput It's ...
0
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1answer
142 views

Cant ssh, connection terminates immediately with exit status 254

The most recent thing I remember is changing the soft and hard memlock ulimit to unlimited. Now I cant ssh into the machine. This is the ssh log. Authenticated to IP ([IP]:22). debug1: channel 0: ...
6
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2answers
182 views

How many commands can be queued up with control operators?

I have been reading up on control operators, and I was wondering if there was a limit to how many commands you could line up with control operators, such as ||, && and ;. In addition, is ...
1
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1answer
19 views

What standard shell command can evaluate escaped Unicode in a stream?

I'm looking for a pipeable command that will convert substrings in the form of ‘\unnnn’ to the actual characters. For example: $ echo 'co\u00ebfficient' | what_command coëfficient
1
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1answer
50 views

Compare file size of multiple files in an array [closed]

Scenario: Ftp site has 100s of files. Once a day, all the .gz files are copied to an AWS site then renamed. Only the date is kept in the file name. Some of the files corrupted during copy. A txt ...
7
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0answers
83 views

regarding portable sed -e… d b or ! b?

In this edit Stéphane Chazelas POSIXifies (again) my sed formatting by inserting an -expression break and another -expression statement. Now, I might just ask him why in the comments, I suppose, but ...
1
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2answers
59 views

Why does sudo ignore aliases?

I am running Ubuntu 10.04 and I use upstart for daemon management. My enterprise application is run as a daemon and must be run as root because of various privileges. E.g.: sudo start ...
1
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1answer
28 views

Save views in multiple screen terminals

As I do in default single view screen terminal of ubuntu; gnome-terminal \ --tab-with-profile=Default --working-directory="some dir" --title="some title" \ --tab-with-profile=Default ...
-4
votes
1answer
39 views

What is the significance of the the leading “4” before the listing of modified files?

After running the following command: find /Users/UserName/Documents -type f -mtime -1 -print0 | xargs -0 du -sk | sort -nr I receive the following output: 4 ...
4
votes
2answers
81 views

Write variable containing large text with \n to a file with common shell interpreters. How do you do it?

Environment: linux shell or better, ash shell in busybox (example system: Openwrt). Given a string variable with large text "${a}" constructed in this way: for index in $(seq 1 40000); do #it is ...
4
votes
0answers
36 views

Show error messages and information that a program was killed on another terminal [duplicate]

If I open a program, say evince, from the GNOME GUI, it is not attached to a terminal. If I send it a signal, it acts accordingly but nothing shows up in my terminal. If I were to open it in a ...
3
votes
1answer
40 views

Fine-tune LS_COLORS for directory suffixes?

I’m fine customizing most settings in LS_COLORS. I don’t need help customizing the colors for different file suffixes. What I would like to do is configure special colors for certain directories, ...
1
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2answers
37 views

awk - read program AND input from the standard input?

Is it possible for awk to read the program and the input from the standard input? I would like to be able to pipe a file to the following function. process_data () { awk -f - <<EOF {print} ...
5
votes
3answers
195 views

sed ranges aren't always able to match only one line

Consider the following range: 1,/pattern/. If pattern matches on the first line, the range matches for the whole file: $ cat 1.sh #!/usr/bin/env bash set -eu seq 1 4 | sed -rn '1,/'"$1"'/p' $ ./1.sh ...
9
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6answers
1k views

How do you remember command options? [closed]

I am curious to know what trick you use to remember options for various commands? Looking up man pages all the time is time consuming and not so cool!
5
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6answers
430 views

How can I reverse the first part of a sentence?

I know that I can reverse any sentence: echo "a,b,c,d" | rev but what if I want to reverse only the first part of a sentence, I have tried this: echo "a,b,c,d Access" | rev and I get this: sseccA ...
-1
votes
1answer
35 views

bash: adduser: command not found on centOS

I installed centos 5.5 on my vmware 8 recently and i am trying to add a new user on the system. I am unable to add the user unless i use su - option. I believe it has to do something with path not set ...
1
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2answers
104 views

Pass a command to ROOT from a shell script and having it stay open

I am writing a bash script to perform some analysis using the program ROOT. I want to run some initial command to load the result of the analysis, then continue using ROOT interactively. The analysis ...
1
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0answers
56 views

How to pass multiple commands via pssh and multiple xterms

I'm attempting to open multiple xterms and run a command as an SAP user via sudo using pssh. So far, I'm able to run PSSH to a file of servers with no check for keys, open every xterm in the servers ...
5
votes
1answer
51 views

Getting the process-id out of command launched with “su -c”

I am running a java program inside a shell and writing the process-id to a text file. So when I do this: nohup java app.Main > /dev/null 2>&1 & echo $! > /var/run/app.pid It works. ...
4
votes
4answers
65 views

Renaming multiple files with rename

I need help renaming files in batch--the other questions I browsed don't exactly address my problem. The names of my files are generated non-deterministically, so I can't predict what they will be ...
1
vote
1answer
70 views

How to find the cpu and memory usage of child processes

Supervisord is running on centos server. If I do ps -e -o %mem,%cpu,cmd | grep supervisord | awk '{memory+=$1;cpu+=$2} END {print memory,cpu}' I get 0 0 just because supervisord is just an ...
4
votes
4answers
251 views

Convert key=value blocks to CSV

I am trying to transpose a content of a file into another. I am new to shell scripting any help would be really appreciated Input file Test.txt: HLRSN = 3 IMSI = 404212109727229 KIVALUE = ...
2
votes
2answers
50 views

Create an absolute symbolic link to the current directory

I am now under a directory with very long path. For future visiting it quicker, I would like to create a link to it. I tried ln -s . ~/mylink ~/mylink actually links to ~. So can I expand ~ into ...
0
votes
0answers
41 views

Detach a process from Sh (not Bash) or “disown” for Sh (not Bash)

Consider a shell script executed by Sh, not Bash (and I can't change it, and can't use a shebang, it's ignored). The & operator works, but disown $! does not and makes Sh complains “disown: not ...
8
votes
3answers
337 views

What is the difference of -a and -e in bash's conditional expressions?

From man bash: CONDITIONAL EXPRESSIONS [...] -a file True if file exists. [...] -e file True if file exists. So what is the difference between [ -a $FILE ...
6
votes
1answer
353 views

Expand ~, . and `..`

Since ~, . and .. are special directories, why are they handled differently in the following example? $ echo ~ /home/tim $ echo .. .. $ echo . . ~ is expanded into the dir, but the other two are ...
2
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2answers
40 views

Select a range of files after sorting them

One thing I notice slower for me if I switch from using a GUI file manager to CLI is: In a GUI file manager, I can quickly select a subset of files under a dir by, first sorting them according to ...
1
vote
1answer
46 views

Who does the linewrap and how to deactivate?

If I connect to a linux device via serial adapter (no matter if pyserial, screen or minicom), and no matter how I change settings like stty when I enter a long command it gets line wrapped ...
2
votes
1answer
142 views

How does execution of !find command work?

The !find command lets the user perform the previously executed find, with all its parameters. How does it work internally, where exactly has this behaviour been programmed?
2
votes
2answers
37 views

Variable assignment outside of case statement

In many languages it is possible to assign the result of a case/switch statement to a variable, rather than repeating the variable assignment many times within the case statement. Is it possible to ...
16
votes
8answers
2k views

How do I repeat the last command without using the arrow keys?

I know I can use Up to iterate through previous commands. Running the last command simply involves Up + Enter. However, I was thinking of buying the Happy Hacking Keyboard as I spend a lot of time in ...
2
votes
2answers
49 views

Read Multiple Entries from an Input File

I wrote a program in Fortran that asks me for latitude and longitude and the name of the output file every time I run it. It works great. What I have been meaning to do is run this program for the ...
0
votes
1answer
29 views

What is the term “Usage”?

I am seeing this a lot in the scripts. Is "usage" a command in unix ? I tried googling it but got ambiguous results. Here is an example : ${1?"Usage: $0 ARGUMENT"}