I have 2 files .c which only contain a printf("x")
I am in bash script and i want to check if the values in the printf are for project1.c =20 and for project 2 =10,and then make some changes depending on the values.
How am i supposed to make the comparison in the if command?
This is what i have tried to do,not sure if it is right way.
for d in $1/*/*
do
gcc project1 project1.c
if[ ./project1 = 20 ];then
$project1 =30
else
$project1 =0
fi
gcc project2 project2.c
if[ ./project2 =10 ];then
$project2 = 70
else
$project2 = 0
fi
sum=$project1 + $project2
echo "project1 : $project1 project2: $project2 total grade: $sum" >> grades.txt
done
fi
Your invocation of gcc is wrong. You have to specify the output file:
gcc -o project1 project1.c
Next, in shell, variable substitution is a different process than assignment. So, you can't write $var=foo. The correct syntax is var=foo.
Then, space is a special character (it is used to separate arguments). So var=foo is not the same than var = foo. So, the correct syntax is:
project1=30
Next, in shell, the pattern $(command) is replaced by the result of command. So. I have to do:
if [ $(./project2) == 10 ]; then
Finally, you can do arithmetic using $((calculus)). So, you have to write:
sum=$(($project1 + $project2))
Take the following makefile snippet:
VAR_LIST = "item1" "item2" "item 3 that has spaces" "item4"
ARGS = $(addprefix echo ,$(VAR_LIST))
What I am trying to achive is for ARGS to contain:
echo "item1" echo "item2" echo "item 3 that has spaces" echo "item4"
What I can't figure out how to resolve is that functions like addprefix act on spaces...
Not sure whether what you need is easily achievable with make because quoting strings have no effect on make functions that process words: " is a part of a word.
I would use a shell or python script for that.
You can do that with the help of gmtt entirely inside GNUmake. It is not as straightforward as in a full programming language, but at least it is portable and independent of external shell flavours and tools.
include gmtt/gmtt.mk
VAR_LIST = "item1" "item2" "item 3 that has spaces" "item4"
# make a prefix-list by splitting at ". This will yield superfluous space
# characters between the items, but we can eliminate them later
prefix-list := $(call chop-str-spc,$(VAR_LIST),A $(-alnum-as-str))
$(info $(prefix-list))
# Now we select the data payload from the prefix-list. Spaces inside items
# are still encoded as $(-spacereplace) characters, which is good as we have
# a normal make list this way
string-list := $(call get-sufx-val,$(prefix-list),A,,100)
$(info $(string-list))
# Using get-sufx-val() is fine, but we can have it even simpler, by dropping
# the prefix, as we have only one in the list anyway:
string-list := $(call drop-prfx,$(prefix-list))
# Now step through the list with a normal for loop, converting $(-spacereplace)
# back to real spaces
$(foreach item,$(string-list),$(if $(strip $(call spc-unmask,$(item))),\
$(info [$(call spc-unmask,$(item))])))
Output:
$ make
A¤item1 A¤§ A¤item2 A¤§ A¤item§3§that§has§spaces A¤§ A¤item4
item1 § item2 § item§3§that§has§spaces § item4
[item1]
[item2]
[item 3 that has spaces]
[item4]
I wrote a short code in .bat file - but I get an error that the if command is incorrect.
my code:
#echo off
set arg1=%1
echo %arg1%
if %arg1% == rot(
echo yes)
the output is:
rot
The syntax of the command is incorrect.
When I looked for the way to write if statement in bat file I saw lots of syntax options but non of them works for me.
I tried:
if "%arg1%" == rot
if "%arg1%" == "rot"
if %arg1% == "rot"
But no one was ok.
I Will be very happy to get help. Thanks.
Your code must look like:
#echo off
set arg1=%1
echo %arg1%
IF "%arg1%" == "rot" (
echo yes
)
both arguments must be in double quotes:
test.bat rot
rot
yes
This is an example of use of DEFAULT_GOAL Variable:
ifeq ($(.DEFAULT_GOAL),)
$(warning no default goal is set)
endif
.PHONY: foo
foo: ; #echo $#
$(warning default goal is $(.DEFAULT_GOAL))
# Reset the default goal.
.DEFAULT_GOAL :=
.PHONY: bar
bar: ; #echo $#
$(warning default goal is $(.DEFAULT_GOAL))
# Set our own.
.DEFAULT_GOAL := foo
The output is:
no default goal is set
default goal is foo
default goal is bar
foo
I stuck up understanding that what is the flow of the echo and $(warning ) function i.e. when $(warning ) function is called the echo $# output is suppressed and last output of echo $# is displayed. Because there is 2 echo statement and 3 $(warning ) function call but only one target id printed by echo the last one foo . Why others are not printed and why the last value is printed as foo why not bar?
The warnings and assignments happen as make reads the Makefile. Only then does it begin to decide which of the rules to execute. The other echo statements are never executed because it only makes the default goal at that point, which is foo.
I've been trying to customize my Bash prompt so that it will look like
[feralin#localhost ~]$ _
with colors. I managed to get constant colors (the same colors every time I see the prompt), but I want the username ('feralin') to appear red, instead of green, if the last command had a nonzero exit status. I came up with:
\e[1;33m[$(if [[ $? == 0 ]]; then echo "\e[0;31m"; else echo "\e[0;32m"; fi)\u\e[m#\e[1;34m\h \e[0;35m\W\e[1;33m]$ \e[m
However, from my observations, the $(if ...; fi) seems to be evaluated once, when the .bashrc is run, and the result is substituted forever after. This makes the name always green, even if the last exit code is nonzero (as in, echo $?). Is this what is happening? Or is it simply something else wrong with my prompt? Long question short, how do I get my prompt to use the last exit code?
As you are starting to border on a complex PS1, you might consider using PROMPT_COMMAND. With this, you set it to a function, and it will be run after each command to generate the prompt.
You could try the following in your ~/.bashrc file:
PROMPT_COMMAND=__prompt_command # Function to generate PS1 after CMDs
__prompt_command() {
local EXIT="$?" # This needs to be first
PS1=""
local RCol='\[\e[0m\]'
local Red='\[\e[0;31m\]'
local Gre='\[\e[0;32m\]'
local BYel='\[\e[1;33m\]'
local BBlu='\[\e[1;34m\]'
local Pur='\[\e[0;35m\]'
if [ $EXIT != 0 ]; then
PS1+="${Red}\u${RCol}" # Add red if exit code non 0
else
PS1+="${Gre}\u${RCol}"
fi
PS1+="${RCol}#${BBlu}\h ${Pur}\W${BYel}$ ${RCol}"
}
This should do what it sounds like you want. Take a look a my bashrc's sub file if you want to see all the things I do with my __prompt_command function.
If you don't want to use the prompt command there are two things you need to take into account:
getting the value of $? before anything else. Otherwise it'll be overridden.
escaping all the $'s in the PS1 (so it's not evaluated when you assign it)
Working example using a variable
PS1="\$(VALU="\$?" ; echo \$VALU ; date ; if [ \$VALU == 0 ]; then echo zero; else echo nonzero; fi) "
Working example without a variable
Here the if needs to be the first thing, before any command that would override the $?.
PS1="\$(if [ \$? == 0 ]; then echo zero; else echo nonzero; fi) "
Notice how the \$() is escaped so it's not executed right away, but each time PS1 is used. Also all the uses of \$?.
Compact solution:
PS1='... $(code=${?##0};echo ${code:+[error: ${code}]})'
This approach does not require PROMPT_COMMAND (apparently this can be slower sometimes) and prints [error: <code>] if the exit code is non-zero, and nothing if it's zero:
... > false
... [error: 1]> true
... >
Change the [error: ${code}] part depending on your liking, with ${code} being the non-zero code to print.
Note the use of ' to ensure the inline $() shell gets executed when PS1 is evaluated later, not when the shell is started.
As bonus, you can make it colorful in red by adding \e[01;31m in front and \e[00m after to reset:
PS1='... \e[01;31m$(code=${?##0};echo ${code:+[error: ${code}]})\e[00m'
--
How it works:
it uses bash parameter substitution
first, the ${?##0} will read the exit code $? of the previous command
the ## will remove any 0 pattern from the beginning, effectively making a 0 result an empty var (thanks #blaskovicz for the trick)
we assign this to a temporary code variable as we need to do another substitution, and they can't be nested
the ${code:+REPLACEMENT} will print the REPLACEMENT part only if the variable code is set (non-empty)
this way we can add some text and brackets around it, and reference the variable again inline: [error: ${code}]
I wanted to keep default Debian colors, print the exact code, and only print it on failure:
# Show exit status on failure.
PROMPT_COMMAND=__prompt_command
__prompt_command() {
local curr_exit="$?"
local BRed='\[\e[0;91m\]'
local RCol='\[\e[0m\]'
PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u#\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
if [ "$curr_exit" != 0 ]; then
PS1="[${BRed}$curr_exit${RCol}]$PS1"
fi
}
The following provides a leading green check mark when the exit code is zero and a red cross in all other cases. The remainder is a standard colorized prompt. The printf statements can be modified to present the two states that were originally requested.
PS1='$(if [ $? -eq 0 ]; then printf "\033[01;32m""\xE2\x9C\x93"; else printf "\033[01;31m""\xE2\x9C\x95"; fi) \[\e[00;32m\]\u#\h\[\e[00;30m\]:\[\e[01;33m\]\w\[\e[01;37m\]\$ '
Why didn't I think about that myself? I found this very interesting and added this feature to my 'info-bar' project. Eyes will turn red if the last command failed.
#!/bin/bash
eyes=(O o ∘ ◦ ⍤ ⍥) en=${#eyes[#]} mouth='_'
face () { # gen random face
[[ $error -gt 0 ]] && ecolor=$RED || ecolor=$YLW
if [[ $1 ]]; then printf "${eyes[$[RANDOM%en]]}$mouth${eyes[$[RANDOM%en]]}"
else printf "$ecolor${eyes[$[RANDOM%en]]}$YLW$mouth$ecolor${eyes[$[RANDOM%en]]}$DEF"
fi
}
info () { error=$?
[[ -d .git ]] && { # If in git project folder add git status to info bar output
git_clr=('GIT' $(git -c color.ui=always status -sb)) # Colored output 4 info
git_tst=('GIT' $(git status -sb)) # Simple output 4 test
}
printf -v line "%${COLUMNS}s" # Set border length
date=$(printf "%(%a %d %b %T)T") # Date & time 4 test
test=" O_o $PWD ${git_tst[*]} $date o_O " # Test string
step=$[$COLUMNS-${#test}]; [[ $step -lt 0 ]] && step=0 # Count spaces
line="$GRN${line// /-}$DEF\n" # Create lines
home="$BLD$BLU$PWD$DEF" # Home dir info
date="$DIM$date$DEF" # Colored date & time
#------+-----+-------+--------+-------------+-----+-------+--------+
# Line | O_o |homedir| Spaces | Git status | Date| o_O | Line |
#------+-----+-------+--------+-------------+-----+-------+--------+
printf "$line $(face) $home %${step}s ${git_clr[*]} $date $(face) \n$line" # Final info string
}
PS1='${debian_chroot:+($debian_chroot)}\n$(info)\n$ '
case "$TERM" in xterm*|rxvt*)
PS1="\[\e]0;${debian_chroot:+($debian_chroot)} $(face 1) \w\a\]$PS1";;
esac
Improved demure answer:
I think this is important because the exit status is not always 0 or 1.
if [ $EXIT != 0 ]; then
PS1+="${Red}${EXIT}:\u${RCol}" # Add red if exit code != 0
else
PS1+="${Gre}${EXIT}:\u${RCol}" # Also displays exit status
fi
To preserve the original prompt format (not just colors),
you could append following to the end of file ~/.bashrc:
PS1_ORIG=$PS1 # original primary prompt value
PROMPT_COMMAND=__update_prompt # Function to be re-evaluated after each command is executed
__update_prompt() {
local PREVIOUS_EXIT_CODE="$?"
if [ $PREVIOUS_EXIT_CODE != 0 ]; then
local RedCol='\[\e[0;31m\]'
local ResetCol='\[\e[0m\]'
local replacement="${RedCol}\u${ResetCol}"
# Replace username color
PS1=${PS1_ORIG//]\\u/]$replacement}
## Alternative: keep same colors, append exit code
#PS1="$PS1_ORIG[${RedCol}error=$PREVIOUS_EXIT_CODE${ResetCol}]$ "
else
PS1=$PS1_ORIG
fi
}
See also the comment about the alternative approach that preserves username color and just appends an error code in red to the end of the original prompt format.
You can achieve a similar result to include a colored (non-zero) exit code in a prompt, without using subshells in the prompt nor prompt_command.
You color the exit code portion of the prompt, while having it only appear when non-zero.
Core 2$ section of the prompt: \\[\\033[0;31;4m\\]\${?#0}\\[\\033[0;33m\\]\$ \\[\\033[0m\\]
Key elements:
return code, if not 0: \${?#0} (specificly "removes prefix of 0")
change color without adding to calculated prompt-width: \\[\\033[0;31m\\]
\\[ - begin block
\\033 - treat as 0-width, in readline calculations for cmdline editing
[0;31;4m - escape code, change color, red fg, underline
\\] - end block
Components:
\\[\\033[0;31;4m\\] - set color 0;31m fg red, underline
\${?#0} - display non-zero status (by removing 0 prefix)
\\[\\033[0;33m\\] - set color 0;33m fg yellow
\$ - $ or # on EUID
\\[\\033[0m\\] - reset color
The full PS1 I use (on one host):
declare -x PS1="\\[\\033[0;35m\\]\\h\\[\\033[1;37m\\] \\[\\033[0;37m\\]\\w \\[\\033[0;33m\\]\\[\\033[0;31;4m\\]\${?#0}\\[\\033[0;33m\\]\$ \\[\\033[0m\\]"
Note: this addresses a natural extension to this question, in a more enduring way then a comment.
Bash
function my_prompt {
local retval=$?
local field1='\u#\h'
local field2='\w'
local field3='$([ $SHLVL -gt 1 ] && echo \ shlvl:$SHLVL)$([ \j -gt 0 ] && echo \ jobs:\j)'"$([ ${retval} -ne 0 ] && echo \ exit:$retval)"
local field4='\$'
PS1=$'\n'"\e[0;35m${field1}\e[m \e[0;34m${field2}\e[m\e[0;31m${field3}\e[m"$'\n'"\[\e[0;36m\]${field4}\[\e[m\] "
}
PROMPT_COMMAND="my_prompt; ${PROMPT_COMMAND}"
Zsh
PROMPT=$'\n''%F{magenta}%n#%m%f %F{blue}%~%f%F{red}%(2L. shlvl:%L.)%(1j. jobs:%j.)%(?.. exit:%?)%f'$'\n''%F{cyan}%(!.#.$)%f '
Images of prompt